rifampin and Disease-Models--Animal

The most effective way to control severity and mortality rate of the novel coronavirus disease (COVID-19) is through sensitive diagnostic approaches and an appropriate treatment protocol. We aimed to identify the effect of adding corticosteroid and Tocilizumab to a standard treatment protocol in treating COVID-19 patients with chronic disease through hematological and lab biomarkers.. This study was performed retrospectively on 68 COVID-19 patients with chronic disease who were treated by different therapeutic protocols. The patients were categorized into four groups: control group represented the patients' lab results at admission before treatment protocols were applied; group 1 included patients treated with anticoagulants, Hydroxychloroquine, and antibiotics; group 2 comprised patients treated with Dexamethasone; and group 3 included patients treated with Dexamethasone and Tocilizumab.. The study paves the way into the effectiveness of combining Dexamethasone with Tocilizumab in treatment COVID-19 patients with chronic diseases.. La forma más eficaz de controlar la gravedad y la tasa de mortalidad de la enfermedad del nuevo coronavirus (COVID-19) es mediante enfoques de diagnóstico sensibles y un protocolo de tratamiento adecuado. Nuestro objetivo fue identificar el efecto de agregar corticosteroides y tocilizumab a un protocolo de tratamiento estándar en el tratamiento de pacientes con COVID-19 con enfermedad crónica a través de biomarcadores hematológicos y de laboratorio.. Este estudio se realizó de forma retrospectiva en 68 pacientes COVID-19 con enfermedad crónica que fueron tratados por diferentes protocolos terapéuticos. Los pacientes se clasificaron en cuatro grupos: el grupo de control representaba los resultados de laboratorio de los pacientes en el momento de la admisión antes de que se aplicaran los protocolos de tratamiento; el grupo 1 incluyó a pacientes tratados con anticoagulantes, hidroxicloroquina y antibióticos; el grupo 2 estaba compuesto por pacientes tratados con dexametasona; y el grupo 3 incluyó a pacientes tratados con dexametasona y tocilizumab.. El estudio allana el camino hacia la eficacia de la combinación de dexametasona con tocilizumab en el tratamiento de pacientes con COVID-19 con enfermedades crónicas.. The Child-Mother Index constitutes a potential useful risk factor indicator for statistical analyses on data after birth. The value of the Child-Mother Index based on the estimated fetal weight before birth deserves evaluation.. Six ceria supports synthesized by various synthesis methodologies were used to deposit cobalt oxide. The catalysts were thoroughly characterized, and their catalytic activity for complete methane oxidation was studied. The supports synthesized by direct calcination and precipitation with ammonia exhibited the best textural and structural properties as well as the highest degree of oxidation. The remaining supports presented poorer textural properties to be employed as catalytic supports. The cobalt deposited over the first two supports presented a good dispersion at the external surface, which induced a significant redox effect that increased the number of Co. Some studies show that children with obesity are more likely to receive a diagnosis of depression, anxiety, or attention-deficit hyperactivity disorder (ADHD). But this does not necessarily mean obesity causes these conditions. Depression, anxiety, or ADHD could cause obesity. A child's environment, including family income or their parents' mental health, could also affect a child's weight and mental health. Understanding the nature of these relationships could help scientists develop better interventions for both obesity and mental health conditions. Genetic studies may help scientists better understand the role of the environment in these conditions, but it's important to consider both the child's and their parents’ genetics in these analyses. This is because parents and children share not only genes, but also environmental conditions. For example, families that carry genetic variants associated with higher body weight might also have lower incomes, if parents have been affected by biases against heavier people in society and the workplace. Children in these families could have worse mental health because of effects of their parent’s weight, rather than their own weight. Looking at both child and adult genetics can help disentangle these processes. Hughes et al. show that a child's own body mass index, a ratio of weight and height, is not strongly associated with the child’s mental health symptoms. They analysed genetic, weight, and health survey data from about 41,000 8-year-old children and their parents. The results suggest that a child's own BMI does not have a large effect on their anxiety symptoms. There was also no clear evidence that a child's BMI affected their symptoms of depression or ADHD. These results contradict previous studies, which did not account for parental genetics. Hughes et al. suggest that, at least for eight-year-olds, factors linked with adult weight and which differ between families may be more critical to a child's mental health than a child’s own weight. For older children and adolescents, this may not be the case, and the individual’s own weight may be more important. As a result, policies designed to reduce obesity in mid-childhood are unlikely to greatly improve the mental health of children. On the other hand, policies targeting the environmental or societal factors contributing to higher body weights, bias against people with higher weights, and poor child mental health directly may be more beneficial.. The development of an efficient photocatalyst for C2 product formation from CO. Оценка антиастенического эффекта последовательной терапии левокарнитином (ЛК) и ацетилкарнитином (АЛК) пациентов с артериальной гипертензией и/или ишемической болезнью сердца (ИБС) с астеническим синдромом (АС).. В открытое сравнительное исследование были включены 120 пациентов в возрасте 54—67 лет с артериальной гипертензией и/или ИБС с АС. Пациенты 1-й группы (. У больных 1-й группы отмечено статистически значимое уменьшение различных проявлений АС. Отличия носили достоверный характер по сравнению как с исходным уровнем, так и со 2-й группой. Установлено эндотелийпротективное действие ЛК и АЛК.. Полученные результаты свидетельствуют, что у таких коморбидных пациентов использование ЛК и АЛК уменьшает выраженность проявлений АС, а установленные эндотелиотропные свойства препаратов позволяют рекомендовать их в составе комплексной персонифицированной терапии пациентов с сердечно-сосудистыми заболеваниями.. Naproxen sodium 440 mg/diphenhydramine 50 mg combination demonstrated improvement in sleep maintenance (WASO) vs. naproxen sodium 550 mg and higher efficiency in average daily pain reduction compared with the comparison groups. The treatment was well tolerated There were no serious or unexpected adverse events reported in the study.. Сравнительный анализ эффективности и безопасности новой комбинации напроксена натрия и дифенгидрамина у пациентов с неспецифическим болевым синдромом в пояснично-крестцовом отделе спины (M54.5 «Боль внизу спины») и нарушением сна (G47.0 «Нарушения засыпания и поддержания сна [бессонница]»).. Проведено проспективное многоцентровое рандомизированное открытое сравнительное в параллельных группах клиническое исследование. Пациенты были рандомизированы в 3 группы. Больные 1-й группы получали напроксен натрия (440 мг) и дифенгидрамин (50 мг), 2-й — напроксен натрия (550 мг), 3-й — парацетамол (1000 мг) и дифенгидрамин (50 мг). Исследуемые препараты пациенты принимали однократно перед сном в течение 3 дней. Все пациенты также принимали 275 мг (1 таблетка) напроксена натрия в качестве препарата фоновой терапии. Первичным критерием эффективности было общее время бодрствования после наступления сна (WASO), измеряемое методом актиграфии. Также использовались критерии оценки продолжительности и качества сна и выраженности боли.. Анализ эффективности проведен для ITT популяции (. Применение комбинации напроксена натрия (440 мг) и дифенгидрамина (50 мг) характеризовалось более выраженным поддержанием сна по сравнению с напроксеном натрия 550 мг и более высокой эффективностью в отношении снижения интенсивности боли по сравнению со 2-й и 3-й группами. Отмечена хорошая переносимость препарата, серьезных нежелательных явлений зарегистрировано не было.

Topics: Acetaminophen; Acetylcarnitine; Acetylcholinesterase; Acids; Acinetobacter baumannii; Acinetobacter Infections; Adaptation, Psychological; Adolescent; Adsorption; Adult; Aged; Alcohol Drinking; Alzheimer Disease; Amikacin; Ammonia; Anaerobiosis; Animals; Anorexia; Anti-Bacterial Agents; Anti-Infective Agents; Anti-Inflammatory Agents; Anti-Inflammatory Agents, Non-Steroidal; Antineoplastic Agents; Anxiety; Aptamers, Nucleotide; Asthenia; Attention Deficit Disorder with Hyperactivity; Bacterial Proteins; Beryllium; beta-Lactamases; Biofuels; Biomass; Biosensing Techniques; Bismuth; Blister; Body Mass Index; Body Surface Area; Boronic Acids; Brain; Breast Neoplasms; Butyrylcholinesterase; Cannabis; Carbapenems; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Carboxylic Acids; Carcinoma, Hepatocellular; Cardiovascular Diseases; Carnitine; Case-Control Studies; Catalysis; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Child; China; Cholinesterase Inhibitors; Clarithromycin; Clostridioides; Clostridioides difficile; Clostridium Infections; Cohort Studies; Colistin; Colitis; Colon; Coloring Agents; Coronary Artery Bypass; Creatinine; Crystalloid Solutions; Cytokines; Depression; Dextran Sulfate; Dextrans; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Diarrhea; Dietary Supplements; Diphenhydramine; Disease Models, Animal; Disease Outbreaks; Double-Blind Method; Doxorubicin; Drosophila; Drug Tapering; Dysbiosis; Electrons; Escherichia coli; Extracellular Vesicles; Fatigue; Female; Fermentation; gamma-Cyclodextrins; Gastrointestinal Microbiome; Glucose; Graft Survival; Graft vs Host Disease; Head and Neck Neoplasms; Heart Arrest, Induced; Hematopoietic Stem Cell Transplantation; High-Intensity Interval Training; Hippocampus; Humans; Hydrogen-Ion Concentration; Hypertension; Incidence; Interferon-gamma; Italy; Kinetics; Klebsiella Infections; Klebsiella pneumoniae; Lab-On-A-Chip Devices; Lactoferrin; Larva; Length of Stay; Lignin; Liver; Liver Neoplasms; Liver Transplantation; Living Donors; Low Back Pain; Lung; Lung Volume Measurements; Macrophages; Male; Melphalan; Men; Mendelian Randomization Analysis; Meropenem; Methane; Mice; Mice, Inbred C57BL; Microbial Sensitivity Tests; Mitochondrial Proteins; Molecular Docking Simulation; Molecular Structure; Mothers; Motivation; Mycoplasma; Mycoplasma hominis; Mycoplasma Infections; NAD; Nanocomposites; Nanoparticles; Nanotubes, Carbon; Naproxen; Neovascularization, Pathologic; Neurons; Nitrates; Nucleolin; Opuntia; Paratyphoid Fever; Phenotype; Phosphatidylinositol 3-Kinases; Phytochemicals; Plant Extracts; Pregnancy; Prevalence; Prospective Studies; Proto-Oncogene Proteins c-akt; Pulmonary Disease, Chronic Obstructive; Rats; Rats, Wistar; Resveratrol; Retrospective Studies; Rifampin; Risk Factors; RNA, Messenger; Selenium; Sleep; Social Behavior; Soil; Soil Pollutants; Squamous Cell Carcinoma of Head and Neck; Staphylococcus aureus; Structure-Activity Relationship; Suicidal Ideation; Suicide; Superoxide Dismutase-1; Surveys and Questionnaires; Swimming; Syndrome; Tannins; Temperature; Transforming Growth Factor beta; Transplantation Conditioning; Treatment Outcome; Triple Negative Breast Neoplasms; Troponin T; Tumor Microenvironment; United Kingdom; Ureaplasma; Ureaplasma urealyticum; Urinary Tract Infections; Viscum; Waste Disposal Facilities; Wastewater; Water; Water Pollutants, Chemical; Wolfiporia; Young Adult

Vascular graft infection (VGI) remains an important complication with a high mortality and morbidity rate. Currently, studies focusing on the role of vascular graft coatings in the prevention of VGI are scarce. Therefore, the aims of this study were to survey and summarise key features of pre-clinical in vivo models that have been used to investigate coating strategies to prevent VGI and to set up an ideal model that can be used in future preclinical research.. A systematic review was conducted in accordance with the Preferred reporting items for Systematic Reviews and Meta-Analysis guidelines. A comprehensive search was performed in MEDLINE (PubMed), Embase, and Web of Science.. For each database, a specific search strategy was developed. Quality was assessed with the Toxicological data Reliability Assessment Tool (ToxRTool). The type of animal model, graft, coating, and pathogen were summarised. The outcome assessment in each study was evaluated.. In total, 4 667 studies were identified, of which 94 papers focusing on in vivo testing were included. Staphylococcus aureus was the organism most used (n = 65; 67.7%). Most of the graft types were polyester grafts. Rifampicin was the most frequently used antibiotic coating (n = 43, 48.3%). In the outcome assessment, most studies mentioned colony forming unit count (n = 88; 91.7%) and clinical outcome (n = 72; 75%). According to the ToxRTool, 21 (22.3%, n = 21/94) studies were considered to be not reliable.. Currently published in vivo models are very miscellaneous. More attention should be paid to the methodology of these pre-clinical reports when transferring novel graft coatings into clinical practice. Variables used in pre-clinical reports (bacterial strain, duration of activity coating) do not correspond well to current clinical studies. Based on the results of this review, a proposal for a complete and comprehensive set up for pre-clinical invivo testing of anti-infectious properties of vascular graft coatings was defined.

Topics: Animals; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Colony Count, Microbial; Disease Models, Animal; Feasibility Studies; Humans; Microbial Sensitivity Tests; Prosthesis-Related Infections; Reproducibility of Results; Rifampin; Staphylococcal Infections; Staphylococcus aureus

Animal infection models in the pharmacokinetic/pharmacodynamic (PK/PD) evaluation of antimicrobial therapy serve an important role in preclinical assessments of new antibiotics, dosing optimization for those that are clinically approved, and setting or confirming susceptibility breakpoints. The goal of animal model studies is to mimic the infectious diseases seen in humans to allow for robust PK/PD studies to find the optimal drug exposures that lead to therapeutic success. The PK/PD index and target drug exposures obtained in validated animal infection models are critical components in optimizing dosing regimen design in order to maximize efficacy while minimize the cost and duration of clinical trials. This review outlines the key components in animal infection models which have been used extensively in antibiotic discovery and development including PK/PD analyses.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Bacterial Infections; Disease Models, Animal; Microbial Sensitivity Tests

Multiple system atrophy (MSA) is a fatal neurodegenerative disorder characterized by autonomic failure and parkinsonism/ataxia; no treatment exists to slow disease progression. A number of factors have prevented or compromised trials targeting disease modification. A major hurdle has been uncertainty about the number of patients needed to achieve adequate power. Information based on natural history studies suggested such numbers to be so large that only international multi-center models seemed feasible. When designing the rifampicin trial in MSA we sought to identify and apply strategies that would improve power and reduce the number needed to treat to allow for an oligocenter approach. Strategies included: (1) inclusion/exclusion criteria designed to enroll patients with relatively early, actively progressing disease; (2) minimizing dropouts; (3) pre-defined interim analysis; and (4) approaches to reduce scoring variability. The model allowed for the number needed to treat to be only 50 patients per treatment arm. Ten selected sites managed to reach the recruitment goal within 12 months. The dropout rate was less than 10%, and the goal of enrolling patients with actively progressing disease was accomplished as reflected by the progression rate in the placebo group. Data from this unfortunately negative trial can now be effectively used to more realistically power future trials. A number of ways to further improve trial design and feasibility have been identified and include rigorous site selection and training, designated primary site investigators, improved error trapping, early site visits, remedial training, and future biomarkers for earlier diagnosis and tracking of disease progression.

Topics: Animals; Biomarkers; Disease Models, Animal; Disease Progression; Humans; Mice, Transgenic; Multiple System Atrophy; Patient Dropouts; Patient Selection; Randomized Controlled Trials as Topic; Research Design; Rifampin; Treatment Outcome

Topics: Acetamides; Aminoglycosides; Animals; Anti-Bacterial Agents; beta-Lactams; Clindamycin; Daptomycin; Disease Models, Animal; Fluoroquinolones; Fosfomycin; Guidelines as Topic; Humans; Linezolid; Microbial Sensitivity Tests; Oxazolidinones; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Teicoplanin; Tetracyclines; Trimethoprim, Sulfamethoxazole Drug Combination; Vancomycin

Implant-associated infection is caused by surface-adhering bacteria persisting as biofilm. Periprosthetic joint infection is difficult to diagnose and treat. The high susceptibility of implanted devices to infection is because of a locally acquired host defense defect, and persistence is mainly because of the rapid formation of a biofilm resistant to host defense and antimicrobial agents. Successful treatment of periprosthetic joint infection requires the optimal surgical procedure combined with long-term antimicrobial therapy directed against surface-adhering microorganisms. Surgical treatment according to an algorithm has been validated in several observational studies. The role of rifampin against device-associated staphylococcal infection has been evaluated in an animal model, in observational studies and in a controlled trial. Given the limited efficacy of traditional antibiotics in implant-associated infections, novel strategies such as coating of the device, vaccination against biofilms, and quorum-sensing inhibitors are promising future options for prevention and treatment.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Bacterial Infections; Bacterial Physiological Phenomena; Biofilms; Disease Models, Animal; Humans; Joint Prosthesis; Prosthesis-Related Infections; Randomized Controlled Trials as Topic; Rifampin; Treatment Outcome

Intermittent tuberculosis treatment regimens have been developed to facilitate treatment supervision. Their efficacy has been substantiated by clinical trials and tuberculosis control programmes, notwithstanding the lack of head-to-head comparison between daily and intermittent regimens. Recently, there has been opposing evidence from observational studies, pharmacokinetic-pharmacodynamic studies and animal models that intermittent treatment increases the risk of relapse, treatment failure or acquired rifamycin resistance, especially among HIV-infected patients. Systematic reviews have been conflicting. PubMed, Ovid MEDLINE and EMBASE were systematically searched for publications in English to evaluate the evidence about dosing schedules and treatment efficacy. Levels of evidence and grades of recommendation were assigned largely according to clinical evidence with reference to the Scottish Intercollegiate Guidelines Network guideline development handbook. A total of 32 articles were included after excluding 331 ineligible articles, 42 non-analytical studies, 22 narrative reviews or expert opinions and 44 articles embedded in systematic reviews. These included 9 systematic reviews, 8 controlled studies, 9 pharmacokinetic-pharmacodynamic studies, 5 mouse studies and 1 article about guinea pig experiments. Findings suggest high levels of evidence for using daily dosing schedules, especially during the initial phase in the presence of cavitation, isoniazid resistance and advanced HIV co-infection, to reduce the risk of treatment failure, recurrence and acquired drug resistance including acquired rifamycin resistance. This review justifies the use of daily schedules in standard tuberculosis treatment regimens (particularly in the initial phase), corroborates prevailing understanding of pharmacokinetics-pharmacodynamics and mycobacterial persisters, and supports exploration of rifapentine-containing regimens in higher dosages and frequency.

Topics: AIDS-Related Opportunistic Infections; Animals; Antitubercular Agents; Child; Disease Models, Animal; Drug Administration Schedule; Humans; Isoniazid; Rifampin; Treatment Outcome; Tuberculosis; Tuberculosis, Multidrug-Resistant

Until 2004, the skin disease known as Buruli ulcer, caused by Mycobacterium ulcerans, could only be treated by surgery and skin grafting. Although this worked reasonably well on early lesions typically found in patients in Australia, the strategy was usually impractical on large lesions resulting from diagnostic delay in patients in rural West Africa. Based on promising preclinical studies, treatment trials in West Africa have shown that a combination of rifampin and streptomycin administered daily for 8 weeks can kill M. ulcerans bacilli, arrest the disease, and promote healing without relapse or reduce the extent of surgical excision. Improved treatment options are the focus of research that has increased tremendously since the WHO began its Global Buruli Ulcer Initiative in 1998.

Topics: Adolescent; Animals; Anti-Bacterial Agents; Buruli Ulcer; Clinical Trials as Topic; Disease Models, Animal; Drug Therapy, Combination; Female; Humans; Mice; Mycobacterium ulcerans; Rifampin; Streptomycin; Treatment Outcome; Young Adult

Vancomycin is often combined with a second antibiotic, most often rifampin or gentamicin, for the treatment of serious methicillin-resistant Staphylococcus aureus infections. Published data from experiments evaluating these and other vancomycin-based combinations, both in vitro and in animal models of infection, often yield inconsistent results, however. More importantly, no data are available from randomized clinical trials to support their use, and some regimens are known to have potential toxicities. Clinicians should carefully reconsider the use of vancomycin-based combination therapies for the treatment of infection due to methicillin-resistant S. aureus.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Therapy, Combination; Gentamicins; Humans; Methicillin-Resistant Staphylococcus aureus; Randomized Controlled Trials as Topic; Rifampin; Staphylococcal Infections; Treatment Outcome; Vancomycin

This review summarizes the in vitro and animal model data available on antibiotic combinations with daptomycin. The majority of studies focus on the clinically relevant combinations of daptomycin with rifampicin or with gentamicin. These studies demonstrate that daptomycin does not adversely affect the activity of other antimicrobial agents that may be administered concomitantly. Overall, additive or indifferent effects with daptomycin combinations were observed; however, synergy was observed for certain isolates of vancomycin-resistant enterococci when exposed to daptomycin and rifampicin. Unexpected synergy was demonstrated against methicillin-resistant Staphylococcus aureus by daptomycin and beta-lactams. Most importantly, no in vitro antagonism of daptomycin with any other agent tested was confirmed in these studies. The most striking in vivo effects were noted in two different complicated infection models; i.e. osteomyelitis and implant infections, where rifampicin combinations with daptomycin increased efficacy and reduced the incidence of rifampicin resistance.

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Daptomycin; Disease Models, Animal; Drug Interactions; Drug Therapy, Combination; Gentamicins; Gram-Positive Bacteria; Gram-Positive Bacterial Infections; Humans; Microbial Sensitivity Tests; Rifampin

The two principal characteristics of tuberculosis treatment are its length (several months) and the need to use several antibiotics simultaneously (multiple drug therapy). Multiple drug therapy is intended to prevent the selection of resistant mutants at the beginning of treatment, when the bacilli population is largest. The length of treatment is due to dormant bacilli, which are much more difficult for antibiotics to kill than actively multiplying bacilli are. Rifampin and pyrazinamide are the most potent drugs against these dormant bacilli. The so-called sterilizing activity of rifampin has reduced the duration of treatment from 18 to 9 months, and the contribution of pyrazinamide reduced this time still further, to 6 months. When one of these drugs cannot be used because of resistance or toxicity, duration of treatment increases to the earlier levels. In the extreme case of multidrug-resistant tuberculosis where neither isoniazid nor rifampin can be used, and sometimes even not pyrazinamide, treatment is recommended for 18 to 24 months. New antituberculosis drugs under development allow us to envision further reduction in the duration of treatment of both drug-resistant and drug-sensitive tuberculosis.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Disease Models, Animal; Drug Resistance, Bacterial; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Humans; Isoniazid; Mice; Mutation; Mycobacterium tuberculosis; Pyrazinamide; Recurrence; Rifampin; Time Factors; Tuberculosis; Tuberculosis, Multidrug-Resistant

Several rifamycin derivatives have been developed during the last 15 years for the treatment of mycobacterial infections. For tuberculosis, rifabutin (RFB) showed strong activity and seemed to be suitable when tuberculosis patients were also treated for their AIDS infection. Rifapentine (RPT) was evaluated in patients with or without AIDS for its intermittent use. It displayed promising activity but must be strengthened in situations, such as AIDS or patients without AIDS but with cavities. Rifalazil (RLZ) has been evaluated in mice but the dosages used were much higher than those tolerated by patients. Regarding Mycobacterium avium infections, RFB showed significant prophylactic activity in humans, RPT displayed some activity in mice and RLZ showed modest activity in mice.

Topics: AIDS-Related Opportunistic Infections; Animals; Disease Models, Animal; Drug Evaluation, Preclinical; France; Humans; Meta-Analysis as Topic; Mycobacterium avium-intracellulare Infection; Randomized Controlled Trials as Topic; Rifampin; Switzerland; Tuberculosis, Pulmonary

The current practice of using INH for tuberculosis prevention is limited by the necessity for at least 6 months of therapy and the problem of INH-induced hepatitis, particularly in older individuals and those with chronic liver disease. Bacteriologic models suggest that, in their persistent form, tubercle bacilli are relatively resistant to INH but become more sensitive to other drugs. Similarly, animal models of latent tuberculosis have suggested that alternative, short-course combinations such as RIF/PZA may be effective, and clinical trials of that two-drug regimen are continuing. At the present time, 3 months of daily RIF, 2 months of RIF/PZA, and 3 months of rifabutin can be considered reasonable alternatives to INH in selected patients. Routine use of these agents in preference to INH cannot yet be endorsed, however, as the standard of care. Without highly effective vaccines for tuberculosis, an important strategy for breaking the cycle of tuberculosis transmission lies in inexpensive, convenient, and effective preventive therapy.

Topics: Animals; Anti-Bacterial Agents; Antibiotic Prophylaxis; Antitubercular Agents; Chronic Disease; Clinical Trials as Topic; Disease Models, Animal; Drug Therapy, Combination; Humans; Isoniazid; Mice; Mycobacterium tuberculosis; Rifampin; Time Factors; Tuberculosis, Pulmonary

Daily doses of 0.5 mg of rifampicin given intraperitoneally to mice after a challenge dose of 104 amastigotes of L. amazonensis led to a significant reduction of the size of local lesions. On the other hand, daily doses of 20 mg/kg to children or 1200 mg to adult patients infected with L. braziliensis did not bring any sign of improvement after 30 days of treatment. Our results formally contradict rifampicin as an alternative drug in Leishmania braziliensis infections.

Topics: Adolescent; Adult; Animals; Child; Disease Models, Animal; Female; Humans; Injections, Intraperitoneal; Leishmania; Leishmania braziliensis; Leishmaniasis, Cutaneous; Leprostatic Agents; Mice; Rifampin

Selection of therapy for legionella infections originated with the clinical observation after the 1976 Philadelphia outbreak that patients treated with erythromycin or tetracycline did better than those who received cephalosporins or aminoglycosides. Early in vitro antibiotic susceptibility studies suggested that rifampin and erythromycin were both active against Legionella pneumophila. However, subsequent in vitro susceptibility studies to other antibiotics have produced variable results, depending on the medium and methodology used. Antibiotic studies within polymorphonuclear leukocytes and alveolar macrophages indicate that those actively concentrated within these cells are predictive of successful therapy. These include erythromycin, rifampin, and certain quinolones. On the other hand, beta-lactam antibiotics such as penicillin, cefoxitin, and imipenem are less likely to be successful because of their lack of concentration within phagocytes. These observations have been confirmed in animal model studies where erythromycin, rifampin, and quinolones have demonstrated efficacy. The addition of rifampin to erythromycin or to doxycycline may be more effective than therapeutic results with either antibiotic alone. Although erythromycin is presently the treatment of choice for legionellosis, the addition of rifampin is recommended, particularly in immunocompromised patients. Doxycycline has served as an appropriate alternative agent, the newer quinolones may be useful and are deserving of carefully designed clinical trials.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Erythromycin; Guinea Pigs; Humans; Legionellosis; Microbial Sensitivity Tests; Phagocytes; Rifampin

Topics: Acetamides; Anemia, Hemolytic; Aniline Compounds; Animals; Clofazimine; Dapsone; Disease Models, Animal; Drug Resistance, Microbial; Drug Therapy, Combination; Humans; Leprosy; Methimazole; Mice; Mycobacterium leprae; Phenyl Ethers; Rifampin; Sulfonamides; Thiosemicarbazones; Thiourea

Considerable developments have occurred in the application of the method for growing Mycobacterium leprae in the mouse foot-pad since it was first described about 10 years ago. The method has been used to study growth curves and histology in normal and in thymectomized irradiated mice, to identify supposed isolates of Myco. leprae that have been made in tissue-culture or in non-living media, to evaluate tests of experimental vaccines, to investigate applications to clinical investigations (the loss of infectivity during chemotherapy as a means of monitoring a drug trial, the demonstration of drug-resistance, and the clinical problem of the patient who responds poorly to therapy), and to study new drugs-e.g., dapsone, acedapsone, clofazimine, and rifampicin.

Topics: Animals; BCG Vaccine; Clofazimine; Dapsone; Disease Models, Animal; Drug Evaluation; Drug Evaluation, Preclinical; Drug Resistance, Microbial; Humans; Leprosy; Mice; Mycobacterium leprae; Radiation Effects; Rifampin; Thymectomy

The most effective way to control severity and mortality rate of the novel coronavirus disease (COVID-19) is through sensitive diagnostic approaches and an appropriate treatment protocol. We aimed to identify the effect of adding corticosteroid and Tocilizumab to a standard treatment protocol in treating COVID-19 patients with chronic disease through hematological and lab biomarkers.. This study was performed retrospectively on 68 COVID-19 patients with chronic disease who were treated by different therapeutic protocols. The patients were categorized into four groups: control group represented the patients' lab results at admission before treatment protocols were applied; group 1 included patients treated with anticoagulants, Hydroxychloroquine, and antibiotics; group 2 comprised patients treated with Dexamethasone; and group 3 included patients treated with Dexamethasone and Tocilizumab.. The study paves the way into the effectiveness of combining Dexamethasone with Tocilizumab in treatment COVID-19 patients with chronic diseases.. La forma más eficaz de controlar la gravedad y la tasa de mortalidad de la enfermedad del nuevo coronavirus (COVID-19) es mediante enfoques de diagnóstico sensibles y un protocolo de tratamiento adecuado. Nuestro objetivo fue identificar el efecto de agregar corticosteroides y tocilizumab a un protocolo de tratamiento estándar en el tratamiento de pacientes con COVID-19 con enfermedad crónica a través de biomarcadores hematológicos y de laboratorio.. Este estudio se realizó de forma retrospectiva en 68 pacientes COVID-19 con enfermedad crónica que fueron tratados por diferentes protocolos terapéuticos. Los pacientes se clasificaron en cuatro grupos: el grupo de control representaba los resultados de laboratorio de los pacientes en el momento de la admisión antes de que se aplicaran los protocolos de tratamiento; el grupo 1 incluyó a pacientes tratados con anticoagulantes, hidroxicloroquina y antibióticos; el grupo 2 estaba compuesto por pacientes tratados con dexametasona; y el grupo 3 incluyó a pacientes tratados con dexametasona y tocilizumab.. El estudio allana el camino hacia la eficacia de la combinación de dexametasona con tocilizumab en el tratamiento de pacientes con COVID-19 con enfermedades crónicas.. The Child-Mother Index constitutes a potential useful risk factor indicator for statistical analyses on data after birth. The value of the Child-Mother Index based on the estimated fetal weight before birth deserves evaluation.. Six ceria supports synthesized by various synthesis methodologies were used to deposit cobalt oxide. The catalysts were thoroughly characterized, and their catalytic activity for complete methane oxidation was studied. The supports synthesized by direct calcination and precipitation with ammonia exhibited the best textural and structural properties as well as the highest degree of oxidation. The remaining supports presented poorer textural properties to be employed as catalytic supports. The cobalt deposited over the first two supports presented a good dispersion at the external surface, which induced a significant redox effect that increased the number of Co. Some studies show that children with obesity are more likely to receive a diagnosis of depression, anxiety, or attention-deficit hyperactivity disorder (ADHD). But this does not necessarily mean obesity causes these conditions. Depression, anxiety, or ADHD could cause obesity. A child's environment, including family income or their parents' mental health, could also affect a child's weight and mental health. Understanding the nature of these relationships could help scientists develop better interventions for both obesity and mental health conditions. Genetic studies may help scientists better understand the role of the environment in these conditions, but it's important to consider both the child's and their parents’ genetics in these analyses. This is because parents and children share not only genes, but also environmental conditions. For example, families that carry genetic variants associated with higher body weight might also have lower incomes, if parents have been affected by biases against heavier people in society and the workplace. Children in these families could have worse mental health because of effects of their parent’s weight, rather than their own weight. Looking at both child and adult genetics can help disentangle these processes. Hughes et al. show that a child's own body mass index, a ratio of weight and height, is not strongly associated with the child’s mental health symptoms. They analysed genetic, weight, and health survey data from about 41,000 8-year-old children and their parents. The results suggest that a child's own BMI does not have a large effect on their anxiety symptoms. There was also no clear evidence that a child's BMI affected their symptoms of depression or ADHD. These results contradict previous studies, which did not account for parental genetics. Hughes et al. suggest that, at least for eight-year-olds, factors linked with adult weight and which differ between families may be more critical to a child's mental health than a child’s own weight. For older children and adolescents, this may not be the case, and the individual’s own weight may be more important. As a result, policies designed to reduce obesity in mid-childhood are unlikely to greatly improve the mental health of children. On the other hand, policies targeting the environmental or societal factors contributing to higher body weights, bias against people with higher weights, and poor child mental health directly may be more beneficial.. The development of an efficient photocatalyst for C2 product formation from CO. Оценка антиастенического эффекта последовательной терапии левокарнитином (ЛК) и ацетилкарнитином (АЛК) пациентов с артериальной гипертензией и/или ишемической болезнью сердца (ИБС) с астеническим синдромом (АС).. В открытое сравнительное исследование были включены 120 пациентов в возрасте 54—67 лет с артериальной гипертензией и/или ИБС с АС. Пациенты 1-й группы (. У больных 1-й группы отмечено статистически значимое уменьшение различных проявлений АС. Отличия носили достоверный характер по сравнению как с исходным уровнем, так и со 2-й группой. Установлено эндотелийпротективное действие ЛК и АЛК.. Полученные результаты свидетельствуют, что у таких коморбидных пациентов использование ЛК и АЛК уменьшает выраженность проявлений АС, а установленные эндотелиотропные свойства препаратов позволяют рекомендовать их в составе комплексной персонифицированной терапии пациентов с сердечно-сосудистыми заболеваниями.. Naproxen sodium 440 mg/diphenhydramine 50 mg combination demonstrated improvement in sleep maintenance (WASO) vs. naproxen sodium 550 mg and higher efficiency in average daily pain reduction compared with the comparison groups. The treatment was well tolerated There were no serious or unexpected adverse events reported in the study.. Сравнительный анализ эффективности и безопасности новой комбинации напроксена натрия и дифенгидрамина у пациентов с неспецифическим болевым синдромом в пояснично-крестцовом отделе спины (M54.5 «Боль внизу спины») и нарушением сна (G47.0 «Нарушения засыпания и поддержания сна [бессонница]»).. Проведено проспективное многоцентровое рандомизированное открытое сравнительное в параллельных группах клиническое исследование. Пациенты были рандомизированы в 3 группы. Больные 1-й группы получали напроксен натрия (440 мг) и дифенгидрамин (50 мг), 2-й — напроксен натрия (550 мг), 3-й — парацетамол (1000 мг) и дифенгидрамин (50 мг). Исследуемые препараты пациенты принимали однократно перед сном в течение 3 дней. Все пациенты также принимали 275 мг (1 таблетка) напроксена натрия в качестве препарата фоновой терапии. Первичным критерием эффективности было общее время бодрствования после наступления сна (WASO), измеряемое методом актиграфии. Также использовались критерии оценки продолжительности и качества сна и выраженности боли.. Анализ эффективности проведен для ITT популяции (. Применение комбинации напроксена натрия (440 мг) и дифенгидрамина (50 мг) характеризовалось более выраженным поддержанием сна по сравнению с напроксеном натрия 550 мг и более высокой эффективностью в отношении снижения интенсивности боли по сравнению со 2-й и 3-й группами. Отмечена хорошая переносимость препарата, серьезных нежелательных явлений зарегистрировано не было.

Topics: Acetaminophen; Acetylcarnitine; Acetylcholinesterase; Acids; Acinetobacter baumannii; Acinetobacter Infections; Adaptation, Psychological; Adolescent; Adsorption; Adult; Aged; Alcohol Drinking; Alzheimer Disease; Amikacin; Ammonia; Anaerobiosis; Animals; Anorexia; Anti-Bacterial Agents; Anti-Infective Agents; Anti-Inflammatory Agents; Anti-Inflammatory Agents, Non-Steroidal; Antineoplastic Agents; Anxiety; Aptamers, Nucleotide; Asthenia; Attention Deficit Disorder with Hyperactivity; Bacterial Proteins; Beryllium; beta-Lactamases; Biofuels; Biomass; Biosensing Techniques; Bismuth; Blister; Body Mass Index; Body Surface Area; Boronic Acids; Brain; Breast Neoplasms; Butyrylcholinesterase; Cannabis; Carbapenems; Carbonyl Cyanide m-Chlorophenyl Hydrazone; Carboxylic Acids; Carcinoma, Hepatocellular; Cardiovascular Diseases; Carnitine; Case-Control Studies; Catalysis; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Child; China; Cholinesterase Inhibitors; Clarithromycin; Clostridioides; Clostridioides difficile; Clostridium Infections; Cohort Studies; Colistin; Colitis; Colon; Coloring Agents; Coronary Artery Bypass; Creatinine; Crystalloid Solutions; Cytokines; Depression; Dextran Sulfate; Dextrans; Diabetes Mellitus, Type 2; Diabetic Retinopathy; Diarrhea; Dietary Supplements; Diphenhydramine; Disease Models, Animal; Disease Outbreaks; Double-Blind Method; Doxorubicin; Drosophila; Drug Tapering; Dysbiosis; Electrons; Escherichia coli; Extracellular Vesicles; Fatigue; Female; Fermentation; gamma-Cyclodextrins; Gastrointestinal Microbiome; Glucose; Graft Survival; Graft vs Host Disease; Head and Neck Neoplasms; Heart Arrest, Induced; Hematopoietic Stem Cell Transplantation; High-Intensity Interval Training; Hippocampus; Humans; Hydrogen-Ion Concentration; Hypertension; Incidence; Interferon-gamma; Italy; Kinetics; Klebsiella Infections; Klebsiella pneumoniae; Lab-On-A-Chip Devices; Lactoferrin; Larva; Length of Stay; Lignin; Liver; Liver Neoplasms; Liver Transplantation; Living Donors; Low Back Pain; Lung; Lung Volume Measurements; Macrophages; Male; Melphalan; Men; Mendelian Randomization Analysis; Meropenem; Methane; Mice; Mice, Inbred C57BL; Microbial Sensitivity Tests; Mitochondrial Proteins; Molecular Docking Simulation; Molecular Structure; Mothers; Motivation; Mycoplasma; Mycoplasma hominis; Mycoplasma Infections; NAD; Nanocomposites; Nanoparticles; Nanotubes, Carbon; Naproxen; Neovascularization, Pathologic; Neurons; Nitrates; Nucleolin; Opuntia; Paratyphoid Fever; Phenotype; Phosphatidylinositol 3-Kinases; Phytochemicals; Plant Extracts; Pregnancy; Prevalence; Prospective Studies; Proto-Oncogene Proteins c-akt; Pulmonary Disease, Chronic Obstructive; Rats; Rats, Wistar; Resveratrol; Retrospective Studies; Rifampin; Risk Factors; RNA, Messenger; Selenium; Sleep; Social Behavior; Soil; Soil Pollutants; Squamous Cell Carcinoma of Head and Neck; Staphylococcus aureus; Structure-Activity Relationship; Suicidal Ideation; Suicide; Superoxide Dismutase-1; Surveys and Questionnaires; Swimming; Syndrome; Tannins; Temperature; Transforming Growth Factor beta; Transplantation Conditioning; Treatment Outcome; Triple Negative Breast Neoplasms; Troponin T; Tumor Microenvironment; United Kingdom; Ureaplasma; Ureaplasma urealyticum; Urinary Tract Infections; Viscum; Waste Disposal Facilities; Wastewater; Water; Water Pollutants, Chemical; Wolfiporia; Young Adult

Designing a more rapid method to test antimycobacterial agents in a murine model would significantly improve the drug development process. We describe a short-course in vivo treatment model that could be used to screen potential antituberculous drugs.. In this model, C57BL/6 mice were infected intranasally with approximately 10(6) viable Mycobacterium tuberculosis organisms. Treatment began 1 day post-infection and was administered for 2 days. Mice were euthanized 3 days post-infection and their right lungs were removed and cell counts determined. Several antimycobacterial agents with superior in vivo activity in a 4 week treatment model were tested to evaluate the short-course treatment model.. Two days of isoniazid (25 mg/kg), rifampicin (20 mg/kg), PNU-100480 (100 mg/kg), gatifloxacin (100 mg/kg), levofloxacin (100 mg/kg) and sparfloxacin (100 mg/kg) were all able to significantly reduce the mycobacterial load in the lungs compared with the untreated control mice.. Use of this model to screen potential chemotherapeutic agents will save time and resources.

Topics: Acetamides; Animals; Antitubercular Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Evaluation, Preclinical; Female; Fluoroquinolones; Gatifloxacin; Isoniazid; Linezolid; Mice; Mice, Inbred C57BL; Oxazolidinones; Rifampin; Time Factors; Tuberculosis

To determine the predictive value of a standard murine model in the treatment of disseminated Myocardium avium complex (MAC) infection, beige mice were infected with MAC strains isolated from human immunodeficiency virus-infected patients and treated with the same antibiotic (ethambutol, clofazimine, or rifampin) that had been administered to the subject from whom that strain had been recovered. While ethambutol had the greatest bacteriologic efficacy in humans (mean decrease +/-SD, 1.0+/-0.5 log 10 cfu/mL of blood), clofazimine had the greatest bacteriostatic efficacy in mice (mean decrease +/- SD, 2.8 +/- 0.7 log(10) cfu/g of tissue). A linear correlation was not observed between bacteriostatic activity in mouse liver or spleen and the degree of bacteriologic response in humans (P > or = to .1). Odds ratios for a response in humans based on a bacteriologic response in mice were not significant for each agent (P > or = to .1, all cases).

Topics: AIDS-Related Opportunistic Infections; Animals; Antitubercular Agents; Clofazimine; Colony Count, Microbial; Disease Models, Animal; Ethambutol; Humans; Liver; Mice; Mycobacterium avium-intracellulare Infection; Rifampin; Species Specificity; Spleen

Daily doses of 0.5 mg of rifampicin given intraperitoneally to mice after a challenge dose of 104 amastigotes of L. amazonensis led to a significant reduction of the size of local lesions. On the other hand, daily doses of 20 mg/kg to children or 1200 mg to adult patients infected with L. braziliensis did not bring any sign of improvement after 30 days of treatment. Our results formally contradict rifampicin as an alternative drug in Leishmania braziliensis infections.

Topics: Adolescent; Adult; Animals; Child; Disease Models, Animal; Female; Humans; Injections, Intraperitoneal; Leishmania; Leishmania braziliensis; Leishmaniasis, Cutaneous; Leprostatic Agents; Mice; Rifampin

The development of novel antibiotic adjuvants is imminent because of the frequent emergence of resistance in Gram-negative bacteria, which severely restricts the efficiency and longevity of commonly used clinical antibiotics. It is reported that famotidine, a clinical inhibitor of gastric acid secretion, enhances the antibacterial activity of rifamycin antibiotics, especially rifampicin, against Gram-negative bacteria and reverses drug resistance. Studies have shown that famotidine disrupts the cell membrane of Acinetobacter baumannii and inhibits the expression of the outer membrane protein

Topics: Acinetobacter baumannii; Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Famotidine; Mice; Microbial Sensitivity Tests; Prospective Studies; Rifampin

Buruli ulcer (BU) is a chronic necrotizing skin disease caused by Mycobacterium ulcerans. Historically, the disease was treated by surgical excision of the skin lesions, until an 8-week combination therapy of rifampicin and streptomycin was introduced in 2004. This treatment modality was effective and reduced recurrence rates. Rifampicin is the most efficacious antibiotic for the treatment of BU and, should rifampicin-resistant M. ulcerans strains emerge, there is currently no replacement for it. As for mycobacterial diseases in general, there is a pressing need for the development of novel, fast-acting drugs. Under market economy conditions, repurposing of new tuberculosis drug candidates is the most promising avenue for alternative BU treatments. Our drug repurposing activities have led to the identification of several actives against M. ulcerans. In particular, the cytochrome bc1 complex inhibitor telacebec (Q203) is a promising drug candidate for the treatment of BU in Africa and Australia. While an active cytochrome-bd oxidase bypass limits the potency of the cytochrome-bc1-specific inhibitor telacebec against M. tuberculosis, classical lineage M. ulcerans strains rely exclusively on cytochrome-bc1 to respire. Hence, telacebec is effective at nanomolar concentration against M. ulcerans, and a high treatment efficacy in an experimental mouse infection model indicates that treatment of BU could be substantially shortened and simplified by telacebec.

Topics: Animals; Buruli Ulcer; Cytochromes; Disease Models, Animal; Drug Repositioning; Mice; Mycobacterium ulcerans; Rifampin; Tuberculosis

Tuberculosis and parasitic infections continue to impose a significant threat to global public health and economic growth. There is an urgent need to develop new treatments to combat these diseases. Here, we report the

Topics: Animals; Chagas Disease; Disease Models, Animal; Mice; Mycobacterium tuberculosis; Nitroimidazoles; Nitroreductases; Trypanosoma cruzi; Tuberculosis

To evaluate the clinical efficacy of bovine serum albumin nanoparticles loaded with isoniazid and rifampicin (INH-RFP-BSA-NPs) in the treatment of spinal tuberculosis in rabbits.. 35 spinal tuberculosis rabbit models were grouped into three groups, including 14 in group A and group B respectively and 7 in group C.All rabbits in group A were treated by INH-RFP-BSA-NPs's injection and in group B were treated with classic dosage form of INH and RFP, while in group C normal saline was given as the blank control. After intervention, the body weighing and CT scan, as well as concentration's measurement of INH and RFP in blood and tissues, were performed in all rabbits at the time of the 6thweek and 12th week, respectively.. In group A, rabbits' weight increased by 0.44 kg and 0.27 kg within 6 weeks and 12 weeks' treatment respectively. The bactericidal concentrations of 1.64 µg•g. The INH-RFP-BSA-NPs has the characteristics of sustained release in vivo and target biodistribution in focus vertebral body. Its therapeutic effect in rabbit spinal tuberculosis is much better than common INH and RFP.

Topics: Animals; Antibiotics, Antitubercular; Delayed-Action Preparations; Disease Models, Animal; Isoniazid; Nanoparticles; Rabbits; Rifampin; Serum Albumin, Bovine; Tuberculosis, Spinal

Topics: Animals; Anti-Bacterial Agents; Arthritis, Infectious; Disease Models, Animal; Inflammation; Mice; Osteolysis; Rifampin

TBI-166, derived from riminophenazine analogues, shows more potent anti-TB activity than clofazimine and is being assessed against tuberculosis (TB) in a phase IIa clinical trial in China. Preclinical regimen studies containing TBI-166 will support the phase IIb clinical trials of TBI-166. In the present study, we compared the efficacy in three murine TB models of an all-oral drug-resistant TB drug regimen of TBI-166 with bedaquiline (BDQ) and pyrazinamide (PZA) with the first-line regimen of isoniazid (INH) with rifampin (RFP) and PZA (HRZ regimen), the most effective reported TBI-166-containing regimen of TBI-166 with BDQ and linezolid (LZD), and the Nix-TB clinical trial regimen of BDQ with pretomanid and LZD (BPaL regimen). In the C3HeB/FeJ murine TB model, for the TBI-166+BDQ+PZA regimen, the lungs of mice were culture negative at 4 weeks, and there were no relapses at 8 weeks of treatment. The reduction in bacterial burden and relapse rate were greater than those of the HRZ regimen and the TBI-166+BDQ+LZD regimen. Compared with the BPaL regimen, the TBI-166+BDQ+PZA regimen had similar or stronger early bactericidal activity, bactericidal activity, and sterilizing activity in the BALB/c murine TB model. The bacterial burden in the TBI-166+BDQ+PZA regimen group decreased significantly more than that in the BPaL regimen group and was almost or totally relapse free (<13.33% after 8 weeks). In conclusion, oral short-course three-drug regimens, including TBI-166 with high efficacy, were identified. The TBI-166+BDQ+PZA regimen is recommended for further study in a TBI-166 phase IIb clinical trial.

Topics: Animals; Antitubercular Agents; Clofazimine; Diarylquinolines; Disease Models, Animal; Isoniazid; Linezolid; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Tuberculosis; Tuberculosis, Multidrug-Resistant

Tuberculosis (TB) claims nearly 1.5 million lives annually. Current TB treatment requires a combination of several drugs administered for at least 6 months.

Topics: Animals; Antitubercular Agents; Dimethyl Fumarate; Disease Models, Animal; Humans; Isoniazid; Mice; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Tuberculosis, Lymph Node

Buruli ulcer (BU) is a skin disease caused by Mycobacterium ulcerans infection that requires long-term antibiotic treatment and/or surgical excision. In this study, we investigated the therapeutic efficacy of the rifamycin derivative, rifalazil (RLZ) (also known as KRM-1648), in an advanced M. ulcerans infection model. Six-week-old female BALB/c mice were infected with 3.25 x 104 colony-forming units (CFU) of M. ulcerans subcutaneously into the bilateral hind footpads. At 33 days post-infection, when the footpads exhibited significant redness and swelling, mice were treated orally with 5 or 10 mg/kg of RLZ for up to 15 weeks. Mice were followed for an additional 15 weeks following treatment cessation. Untreated mice exhibited a progressive increase in footpad redness, swelling, and erosion over time, and all untreated mice reached to endpoint within 5-8 weeks post-bacterial injection. In the RLZ-treated mice, footpad redness and swelling and general condition improved or completely healed, and no recurrence occurred following treatment cessation. After 3 weeks of treatment, the CFU counts from the footpads of recovered RLZ-treated mice showed a 104 decrease compared with those of untreated mice. We observed a further reduction in CFU counts to the detection limit following 6 to 15 weeks of treatment, which did not increase 15 weeks after discontinuing the treatment. Histopathologically, bacteria in the treated mice became fragmented one week after RLZ-treatment. At the final point of the experiment, all the treated mice (5mg/kg/day; n = 6, 10mg/kg/day; n = 7) survived and had no signs of M. ulcerans infection. These results indicate that the rifamycin analogue, RLZ, is efficacious in the treatment of an advanced M. ulcerans infection mouse model.

Topics: Animals; Anti-Bacterial Agents; Buruli Ulcer; Disease Models, Animal; Drug Therapy, Combination; Female; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Rifampin; Rifamycins

The Staphylococcus aureus can switch to a transient genotype-invariant dormancy, known as a persister, to survive treatment with high doses of antibiotics. This transient persister is an important reason underlying its resistance. There is an urgent need to find new antibacterial agents capable of eradicating methicillin-resistant S. aureus (MRSA) persisters. In this study, 37 new derivatives of cajaninstilbene acid (CSA) were designed and synthesized, and their biological activity against MRSA persisters was evaluated. Most of the newly synthesized derivatives exhibit more potent antimicrobial properties against S. aureus and MRSA than CSA itself, and 23 of the 37 derivatives show a tendency to eradicate MRSA persisters. A representative compound (A6) was demonstrated to target bacterial cell membranes. It eradicated the adherent biofilm of MRSA in a concentration dependent manner, and showed a synergistic antibacterial effect with piperacilin. In a model mouse abscess caused by MRSA persisters, A6 effectively reduced the bacterial load in vivo. These results indicate that A6 is a potential candidate for treatment of MRSA persister infections.

Topics: Animals; Anti-Bacterial Agents; Biofilms; Cell Survival; Cell Wall; Disease Models, Animal; Methicillin-Resistant Staphylococcus aureus; Mice; Microbial Sensitivity Tests; RAW 264.7 Cells; Salicylates; Skin Diseases; Staphylococcal Infections; Staphylococcus aureus; Stilbenes; Structure-Activity Relationship

Osteoarticular Tuberculosis (TB) is a challenging issue because of its chronicity and recurrence. Many drug delivery systems (DDSs) have been developed for general chemotherapy. Herein, we take advantage of instant hydrogelation to

Topics: Animals; Antitubercular Agents; Biocompatible Materials; Calcium Phosphates; Cell Line; Cell Survival; Chitosan; Disease Models, Animal; Drug Carriers; Drug Liberation; Femur; Glycerophosphates; Hydrogels; Isoniazid; Mice; Mycobacterium tuberculosis; Porosity; Prostheses and Implants; Rifampin; Tuberculosis, Osteoarticular

The Na

Topics: Animals; Anticoagulants; Biological Transport; Cholestasis; Disease Models, Animal; Humans; Male; Organic Anion Transporters, Sodium-Dependent; Rats; Rats, Sprague-Dawley; Rifampin

Alzheimer's disease (AD) is characterized by amyloid-β (Aβ) deposition. The metabolism of Aβ is critically affected by autophagy. Although rifampicin is known to mediate neuroinflammation, the underlying mechanism by which rifampicin regulates the cognitive sequelae remains unknown.. Based on our previous findings that rifampicin possesses neuroprotective effects on improving cognitive function after neuroinflammation, we aimed to examine in this study whether rifampicin can inhibit Aβ accumulation by enhancing autophagy in a mouse model of lipopolysaccharide (LPS)-induced cognitive impairment.. Adult C57BL/6 mice were intraperitoneally injected with rifampicin, chloroquine, and/or LPS every day for 7 days. Pathological and biochemical assays and behavioral tests were performed to determine the therapeutic effect and mechanism of rifampicin on the hippocampus of LPS-induced mice.. We found that rifampicin ameliorated cognitive impairments in the LPS-induced mice. In addition, rifampicin attenuated the inhibition of autophagosome formation, suppressed the accumulation of Aβ1-42, and protected the hippocampal neurons against LPS-induced damage. Our results further demonstrated that rifampicin improved the neurological function by promoting autophagy through the inhibition of Akt/mTOR/p70S6K signaling pathway in the hippocampus of LPS-induced mice.. Rifampicin ameliorates cognitive impairment by suppression of Aβ1-42 accumulation through inhibition of Akt/mTOR/p70S6K signaling and enhancement of autophagy in the hippocampus of LPS-induced mice.

Topics: Amyloid beta-Peptides; Animals; Autophagosomes; Autophagy; Blotting, Western; Cognitive Dysfunction; Disease Models, Animal; Fluorescent Antibody Technique; Hippocampus; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Microscopy, Electron, Transmission; Morris Water Maze Test; Rifampin

Adhatoda vasica Nees is widely used herb of indigenous system to treat various ailments especially upper respiratory tract infections. Not only, anti-tubercular efficacy of crude extract and phytoconstituents of A. vasica has been documented but its hepatoprotective role against various drugs mediated hepatic alterations in different animal models has also been observed.. Isoniazid, rifampicin and pyrazinamide (H-R-Z) are anti-tubercular drugs normally prescribed by health professionals for the treatment of tuberculosis, however along with their medical effectiveness these drugs also exhibit hepatotoxicity among TB patients. Unexpectedly, substantial toxicological data on the metabolism of anti-TB drugs are available but the mystery behind these xenobiotics is too complex and partly implicit. In this study, we further explored the hepatotoxic effects of these xeno-metabolic products and their amelioration by Adhatoda vasica Nees by elucidating its mechanistic action.. We generated a hepatotoxic rodent model by oral administration of H, R and Z (30.85, 61.7 and 132.65 mg/kg body weight) drugs for 25 days in Wistar rats. Additionally, to achieve hepatoprotection two different doses of Adhatoda vasica Nees ethanolic leaf extract (200 and 300 mg/kg body weight) were used along with H-R-Z dosage, orally and once daily for 25 days and tried to ascertain their mechanistic action. For this, initially phytoconstituents of the extract were evaluated followed by extract standardization using RP-HPLC and FTIR methods. Furthermore, antioxidant activity of the extract was analyzed by DPPH assay. Finally, different treated groups were analyzed for hepatic oxidative stress markers, antioxidant markers, histopathological changes and gene expression study including CYP2E1, CYP7A1, NAT, NR1I2 and UGT1A1 genes involved in phase I and phase II xeno-metabolism.. Estimated content of vasicine in RP-HPLC method and free-radical scavenging activity in DPPH assay was found to be 134.519 ± 0.00269μg/10mg of leaf extract and 47.81 μg/mL respectively. In H-R-Z treated group, a significant increase in the levels of thiobarbituric acid, significant reduction in the levels of GSH, and enzymatic markers and marked changes in hepatic histological architecture were observed. In addition, there was significance up-regulation of CYP7A and NAT genes, down-regulation of CYP2E1 gene and insignificant expression levels of NR1I2 and UGT1A1 genes were observed in H-R-Z group. Conversely, high dose of A. vasica extract effectively diminished these alterations by declining oxidative stress and boosting of antioxidant levels. In addition, it acted as bi-functional inducer of both phase I (CYP2E1) and phase II (NAT and UGT1A1) enzyme systems.. Hence, we concluded that anti-TB drugs exposure has potential to generate reactive metabolites that eventually cause hepatotoxicity by altering oxidant-antioxidant levels and their own metabolism. This study not only emphasized on xeno-metabolism mediated hepatic alterations but also explore the benefit of A. vasica on these toxic insults.

Topics: Alkaloids; Animals; Antitubercular Agents; Arylamine N-Acetyltransferase; Chemical and Drug Induced Liver Injury; Cholesterol 7-alpha-Hydroxylase; Cytochrome P-450 CYP2E1; Disease Models, Animal; Female; Free Radical Scavengers; Gene Expression Regulation; Glucuronosyltransferase; Isoniazid; Justicia; Oxidative Stress; Plant Extracts; Plant Leaves; Pregnane X Receptor; Pyrazinamide; Quinazolines; Rats, Wistar; Rifampin

Prolonged treatment with rifampicin (RFP), a first-line antibacterial agent used in the treatment of drug-sensitive tuberculosis, may cause various side effects, including metabolic disorders. The nuclear factor (erythroid-derived 2)-like 2 (NFE2L2, also known as NRF2) plays an essential regulatory role in cellular adaptive responses to stresses via the antioxidant response element (ARE). Our previous studies discovered that NRF2 regulates the expression of CCAAT-enhancer-binding protein β (Cebpb) and peroxisome proliferator-activated receptor gamma (Pparg) in the process of adipogenesis. Here, we found that prolonged RFP treatment in adult male mice fed a high-fat diet developed insulin resistance, but reduced fat accumulation and decreased expression of multiple adipogenic genes in white adipose tissues. In 3 T3-L1 preadipocytes, RFP reduced the induction of Cebpb, Pparg and Cebpa at mRNA and protein levels in the early and/or later stage of hormonal cocktail-induced adipogenesis. Mechanistic investigations demonstrated that RFP inhibits NRF2-ARE luciferase reporter activity and expression of NRF2 downstream genes under normal culture condition and in the early stage of adipogenesis in 3 T3-L1 preadipocytes, suggesting that RFP can disturb adipogenic differentiation via NRF2-ARE interference. Taken together, we demonstrate a potential mechanism that RFP impairs adipose function by which RFP likely inhibits NRF2-ARE pathway and thereby interrupts its downstream adipogenic transcription network.

Topics: 3T3-L1 Cells; Adipocytes, White; Adipogenesis; Adipose Tissue, White; Adiposity; Animals; Antibiotics, Antitubercular; Antioxidant Response Elements; Diet, High-Fat; Disease Models, Animal; Insulin Resistance; Male; Mice; Mice, Inbred C57BL; NF-E2-Related Factor 2; Obesity; Rifampin; Signal Transduction; Transcription, Genetic

Tuberculosis is a chronic disease that displays several features commonly associated with biofilm-associated infections: immune system evasion, antibiotic treatment failures, and recurrence of infection. However, although Mycobacterium tuberculosis (Mtb) can form cellulose-containing biofilms in vitro, it remains unclear whether biofilms are formed during infection in vivo. Here, we demonstrate the formation of Mtb biofilms in animal models of infection and in patients, and that biofilm formation can contribute to drug tolerance. First, we show that cellulose is also a structural component of the extracellular matrix of in vitro biofilms of fast and slow-growing nontuberculous mycobacteria. Then, we use cellulose as a biomarker to detect Mtb biofilms in the lungs of experimentally infected mice and non-human primates, as well as in lung tissue sections obtained from patients with tuberculosis. Mtb strains defective in biofilm formation are attenuated for survival in mice, suggesting that biofilms protect bacilli from the host immune system. Furthermore, the administration of nebulized cellulase enhances the antimycobacterial activity of isoniazid and rifampicin in infected mice, supporting a role for biofilms in phenotypic drug tolerance. Our findings thus indicate that Mtb biofilms are relevant to human tuberculosis.

Topics: Animals; Biofilms; Cellulase; Cellulose; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Synergism; Humans; Isoniazid; Mice; Mice, Inbred C57BL; Mycobacterium abscessus; Mycobacterium avium; Mycobacterium fortuitum; Mycobacterium tuberculosis; Rifampin; Tuberculosis, Pulmonary

Aberrant microglial responses promote neuroinflammation in neurodegenerative diseases. However, rifampicin's effect on cognitive and motor sequelae of inflammation remains unknown. Therefore, we investigated whether rifampicin exerts neuroprotection against lipopolysaccharide (LPS)-induced cognitive and motor impairments.. A mouse model of LPS-induced cognitive and motor impairment was established. Adult C57BL/6 mice were injected intraperitoneally with 25 mg/kg rifampicin 30 min before intraperitoneal microinjection of LPS (750 μg/kg) daily until study end. Treatments and behavioral experiments were performed once daily for 7 days. Behavioral tests and pathological/biochemical assays were performed to evaluate LPS-induced damage to the hippocampus and substantia nigra (SN).. Rifampicin protects against LPS-induced neuroinflammation and attenuates cognitive and motor impairments by inhibiting the TLR4/MyD88/NF-κB signaling pathway. Our findings might aid the development of novel therapies to treat progressive neurodegenerative diseases.

Topics: Animals; Cognitive Dysfunction; Disease Models, Animal; Hippocampus; Inflammation; Inflammation Mediators; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Microglia; Motor Disorders; Myeloid Differentiation Factor 88; Neurodegenerative Diseases; Neuroprotection; NF-kappa B; Rifampin; Signal Transduction; Substantia Nigra; Toll-Like Receptor 4

α-Synuclein oligomers are thought to play an important role in the pathogenesis of dementia with Lewy bodies (DLB). There is no effective cure for DLB at present. Previously, we demonstrated that in APP- and tau-transgenic mice, oral or intranasal rifampicin reduced brain Aβ and tau oligomers and improved mouse cognition. In the present study, we expanded our research to DLB. Rifampicin was intranasally administered to 6-month-old A53T-mutant α-synuclein-transgenic mice at 0.1 mg/day for 1 month. The mice displayed memory impairment but no motor deficit at this age, indicating a suitable model of DLB. α-Synuclein pathologies were examined by the immunohistochemical/biochemical analyses of brain tissues. Cognitive function was evaluated by the Morris water maze test. Intranasal rifampicin significantly reduced the levels of [pSer129] α-synuclein in the hippocampus and α-synuclein oligomers in the visual cortex and hippocampus. The level of the presynaptic marker synaptophysin in the hippocampus was recovered to the level in non-transgenic littermates. In the Morris water maze, a significant improvement in spatial reference memory was observed in rifampicin-treated mice. Taken together with our previous findings, these results suggest that intranasal rifampicin is a promising remedy for the prevention of neurodegenerative dementia, including Alzheimer's disease, frontotemporal dementia, and DLB.

Topics: Administration, Intranasal; alpha-Synuclein; Animals; Cognition; Dementia; Disease Models, Animal; Female; Lewy Bodies; Lewy Body Disease; Male; Mice, Transgenic; Protein Multimerization; Rifampin

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

Host-directed therapies are a comparatively new and promising method for the treatment of tuberculosis. A variety of host pathways, vaccines and drugs have the potential to provide novel adjunctive therapies for the treatment of tuberculosis. In this connection, we have earlier reported the immunotherapeutic potential of N-formylated N-terminal peptide of glutamine synthetase of Mycobacterim tuberculosis H37Rv (Mir SA and Sharma S, 2014). Now in the present study, we investigated the immunotherapeutic effect of N-terminally formylated internal-peptide 'f- MLLLPD' of mycobacterial glutamine synthetase (Rv2220) in mouse model of tuberculosis.. The N-terminally formylated peptide, f-MLLLPD was tested for its potential to generate Reactive Oxygen Species (ROS) in murine neutrophils. Further, its therapeutic effect alone or in combination with anti-tubercular drugs was evaluated in mouse model of tuberculosis.. The f-MLLLPD peptide treatment alone and in combination with ATDs reduced the bacterial load (indicated as colony forming units) in lungs of infected mice by 0.58 (p<0.01) and 2.92 (p<0.001) log10 units respectively and in their spleens by 0.46 (p<0.05) and 2.46 (p<0.001) log10 units respectively. In addition, the observed histopathological results correlated well with the CFU data.. The results of the current study show that f-MLLLPD peptide confers an additional therapeutic efficacy to the anti-tuberculosis drugs.

Topics: Animals; Bacterial Load; Bacterial Proteins; Disease Models, Animal; Drug Therapy, Combination; Female; Glutamate-Ammonia Ligase; Isoniazid; Lung; Mice; Mycobacterium tuberculosis; N-Formylmethionine Leucyl-Phenylalanine; Neutrophils; Reactive Oxygen Species; Rifampin; Spleen; Tuberculosis

Isoniazid (INH) and rifampicin (RIF) continue to be first line anti‑tuberculosis (TB) drugs. However, the use of these drugs is associated with hepatotoxicity. Nuclear factor‑κB (NF‑κB) plays a crucial role in regulating immunity and inflammation. It has been reported that pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF‑κB, exerts a hepatoprotective effect on acute and chronic liver damage. The aim of the present study was to explore the INH/RIF‑induced protective effects and mechanisms of PDTC on liver injury. Rats were intragastrically administered INH (50 mg/kg/day) and RIF (50 mg/kg/day) daily for 28 days. PDTC (50 mg/kg/day) was intraperitoneally injected 2 h after the co‑administration of INH and RIF to compare liver biochemical indicators in the serum, histopathological damage, NF‑κB activity, oxidative stress, hepatic mRNA expression of tumor necrosis factor (TNF)‑α, bile salt export pump (BSEP), and protein expression of BSEP. It was found that the inhibition of NF‑κB activation by PDTC treatment markedly alleviated liver biochemical and histological injury, decreased oxidative stress and mRNA levels of TNF‑α, and prevented decreases in BSEP mRNA and protein expression induced by the co‑administration of INH and RIF. Collectively, the present data suggested that INH/RIF‑induced liver injury is dependent on the activation of NF‑κB. PDTC exerted a therapeutic effect on INH/RIF‑induced liver injury by increasing BSEP expression, and exhibiting antioxidant and anti‑inflammatory activities.

Topics: Animals; Antioxidants; ATP Binding Cassette Transporter, Subfamily B, Member 11; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Humans; Isoniazid; Liver; NF-kappa B; Oxidative Stress; Pyrrolidines; Rats; Rifampin; Thiocarbamates; Tumor Necrosis Factor-alpha

In hernia surgery, soaking of meshes in antibiotics before implantation is a prophylactic strategy for minimizing the risk of infection while providing minimal, local, drug doses. This study describes the development and application of an antibacterial mesh coating comprising a carboxymethylcellulose gel loaded with rifampicin in a preclinical model of Staphylococcus aureus and S. epidermidis infection in rabbits.. In vitro, rifampicin-carboxymethylcellulose gel demonstrated great activity against Staphylococcus aureus/S. epidermidis, while being innocuous for fibroblasts. In vivo, rifampicin-carboxymethylcellulose gel-coated implants displayed full bacterial clearance and optimal tissue integration, irrespective of the strain of Staphylococcus. In contrast, uncoated and carboxymethylcellulose gel-coated implants exhibited macro/microscopic signs of infection and impaired tissue integration. Macrophage responses were less in rifampicin-carboxymethylcellulose gel implants than in uncoated mesh (Staphylococcus aureus/S. epidermidis; P < .01) and carboxymethylcellulose gel (S. epidermidis; P < .05) implants. Bloodstream levels of rifampicin were undetectable.. Soaking meshes in rifampicin-carboxymethylcellulose gel inhibited effectively the bacterial adhesion to the mesh without compromising the tissue repair. This antibiotic gel constitutes an easy-to-use and effective prophylactic strategy that potentially reduce the prevalence of postoperative mesh infection.

Topics: Animals; Anti-Bacterial Agents; Antibiotic Prophylaxis; Carboxymethylcellulose Sodium; Disease Models, Animal; Hernia, Abdominal; Herniorrhaphy; Humans; Male; Microbial Sensitivity Tests; Rabbits; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Staphylococcus epidermidis; Surgical Mesh; Surgical Wound Infection

Topics: Administration, Topical; Animals; Antiprotozoal Agents; Chitosan; Disease Models, Animal; Drug Delivery Systems; Flow Cytometry; Humans; Leishmaniasis, Cutaneous; Macrophages; Mice; Nanogels; Nanoparticles; Polyethylene Glycols; Polyethyleneimine; Rats; Rifampin

Proper characterization of drug effects on Mycobacterium tuberculosis relies on the characterization of phenotypically resistant bacteria to correctly establish exposure-response relationships. The aim of this work was to evaluate the potential difference in phenotypic resistance in in vitro compared to murine in vivo models using CFU data alone or CFU together with most probable number (MPN) data following resuscitation with culture supernatant. Predictions of in vitro and in vivo phenotypic resistance i.e. persisters, using the Multistate Tuberculosis Pharmacometric (MTP) model framework was evaluated based on bacterial cultures grown with and without drug exposure using CFU alone or CFU plus MPN data. Phenotypic resistance and total bacterial number in in vitro natural growth observations, i.e. without drug, was well predicted by the MTP model using only CFU data. Capturing the murine in vivo total bacterial number and persisters during natural growth did however require re-estimation of model parameter using both the CFU and MPN observations implying that the ratio of persisters to total bacterial burden is different in vitro compared to murine in vivo. The evaluation of the in vitro rifampicin drug effect revealed that higher resolution in the persister drug effect was seen using CFU and MPN compared to CFU alone although drug effects on the other bacterial populations were well predicted using only CFU data. The ratio of persistent bacteria to total bacteria was predicted to be different between in vitro and murine in vivo. This difference could have implications for subsequent translational efforts in tuberculosis drug development.

Topics: Animals; Antitubercular Agents; Colony Count, Microbial; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Resistance, Bacterial; Humans; Lung; Mice; Microbial Sensitivity Tests; Models, Biological; Mycobacterium tuberculosis; Rifampin; Tuberculosis, Pulmonary

Industry screens of large chemical libraries have traditionally relied on rich media to ensure rapid bacterial growth in high-throughput testing. We used eukaryotic, nutrient-limited growth media in a compound screen that unmasked a previously unknown hyperactivity of the old antibiotic, rifabutin (RBT), against highly resistant Acinetobacter baumannii. In nutrient-limited, but not rich, media, RBT was 200-fold more potent than rifampin. RBT was also substantially more effective in vivo. The mechanism of enhanced efficacy was a Trojan horse-like import of RBT, but not rifampin, through fhuE, only in nutrient-limited conditions. These results are of fundamental importance to efforts to discover antibacterial agents.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Bacterial Proteins; Colistin; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Gene Deletion; Gene Expression Regulation, Bacterial; High-Throughput Screening Assays; Male; Mice; Mice, Inbred C3H; Microbial Sensitivity Tests; Nutrients; Receptors, Cell Surface; Rifabutin; Rifampin

Efforts at host-directed therapy of tuberculosis have produced little control of the disease in experimental animals to date. This is not surprising, given that few specific host targets have been validated, and reciprocally, many of the compounds tested potentially impact multiple targets with both beneficial and detrimental consequences. This puts a premium on identifying appropriate molecular targets and subjecting them to more selective modulation. We discovered an aminopyrimidine small molecule, 2062, that had no direct antimycobacterial activity, but synergized with rifampin to reduce bacterial burden in Mtb infected macrophages and mice and also dampened lung immunopathology. We used 2062 and its inactive congeners as tool compounds to identify host targets. By biochemical, pharmacologic, transcriptomic and genetic approaches, we found that 2062's beneficial effects on Mtb control and clearance in macrophages and in mice are associated with activation of transcription factor EB via an organellar stress response. 2062-dependent TFEB activation led to improved autophagy, lysosomal acidification and lysosomal degradation, promoting bacterial clearance in macrophages. Deletion of TFEB resulted in the loss of IFNγ-dependent control of Mtb replication in macrophages. 2062 also targeted multiple kinases, such as PIKfyve, VPS34, JAKs and Tyk2, whose inhibition likely limited 2062's efficacy in vivo. These findings support a search for selective activators of TFEB for HDT of TB.

Topics: Animals; Antitubercular Agents; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Disease Models, Animal; Female; Mice; Mycobacterium tuberculosis; Rifampin; Tuberculosis

Buruli ulcer (BU), caused by Mycobacterium ulcerans, is currently treated with a daily combination of rifampin and either injectable streptomycin or oral clarithromycin. An intermittent oral regimen would facilitate treatment supervision. We first evaluated the bactericidal activity of newer antimicrobials against M. ulcerans using a BU animal model. The imidazopyridine amine telacebec (Q203) exhibited high bactericidal activity whereas tedizolid (an oxazolidinone closely related to linezolid), selamectin and ivermectin (two avermectine compounds) and the benzothiazinone PBTZ169 were not active. Consequently, telacebec was evaluated for its bactericidal and sterilizing activities in combined intermittent regimens. Telacebec given twice a week in combination with a long-half-life compound, either rifapentine or bedaquiline, sterilized mouse footpads in 8 weeks, i.e. after a total of only 16 doses, and prevented relapse during a period of 20 weeks after the end of treatment. These results are very promising for future intermittent oral regimens which would greatly simplify BU treatment in the field.

Topics: Animals; Antitubercular Agents; Buruli Ulcer; Diarylquinolines; Disease Models, Animal; Drug Therapy, Combination; Female; Imidazoles; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Oxazolidinones; Piperidines; Pyridines; Rifampin; Tetrazoles

Owing to patient intolerance or drug interactions, alternative agents to rifampin are needed for management of staphylococcal periprosthetic joint infection. In the current study, we evaluated rifabutin, rifapentine and rifampin, with and without vancomycin, in a rat model of foreign body osteomyelitis.. Proximal tibiae were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) and a Kirschner wire (K-wire) implanted in each. After 4 weeks of infection, rifampin, rifabutin, or rifapentine were administered, alone or with vancomycin. Tibiae and K-wires were cultured, and medians were reported as log10 colony-forming units (CFUs) per gram of bone or log10 CFUs per K-wire, respectively.. Rifampin, rifabutin or rifapentine administered with vancomycin yielded less MRSA from bones (0.10, 3.02, and 0.10 log10 CFUs/g, respectively) than did no treatment (4.36 log10 CFUs/g) or vancomycin alone (4.64 log10 CFUs/g) (both P ≤ .02). The K-wires of animals receiving no treatment or vancomycin monotherapy recovered medians of 1.76 and 2.91 log10 CFUs/g per K-wire, respectively. In contrast, rifampin, rifabutin and rifapentine administered with vancomycin yielded medians of 0.1 log10 CFUs per K-wire, respectively. Rifampin resistance was detected in a single animal in the rifampin monotherapy group.. Rifabutin or rifapentine with vancomycin were as active as rifampin with vancomycin against MRSA in rat foreign body osteomyelitis, suggesting that rifabutin and/or rifapentine may be alternatives to rifampin in the clinical management of staphylococcal periprosthetic joint infections.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Therapy, Combination; Foreign Bodies; Male; Methicillin-Resistant Staphylococcus aureus; Osteomyelitis; Rats; Rats, Wistar; Rifabutin; Rifampin; Staphylococcal Infections; Vancomycin

Anti-tuberculosis drug-induced liver injury (ATB-DILI) is a common adverse reaction of anti-tuberculosis drug treatment. Studies have shown that isoniazid (INH) and rifampicin (RFP) are mainly metabolized in the liver and a large amount of intracellular glutathione is used up during the metabolism of these drugs, resulting in lipid peroxidation and hepatocyte death. Ferroptosis is a novel form of programmed cell death caused by iron-ion-dependent lipid peroxidation. In this study, we explored lipid peroxidation and ferroptosis during ATB-DILI. Morphology of ferroptosis was discovered in ATB-DILI mouse livers by transmission electron microscopy. Flow cytometry was used to assess the molecular markers of lipid peroxidation and ferroptosis including reactive oxygen species, lipid peroxidation, and cellular iron content. Glutathione peroxidase 4 (GPX4) was depleted, while acyl-CoA synthetase long chain family member 4 (ACSL4) was overexpressed in the ATB-DILI tissues. And glutathione supplementation significantly reduced the level of lipid peroxidation and the risk of liver damage. Retrospective study of tuberculosis patients who underwent INH and RFP treatment also revealed an association between the intake of glutathione and a negative ATB-DILI rate. In addition, iron supplementation enhanced the degree of lipid peroxidation and liver injury induced by INH and RFP in vivo and clinical retrospective study. Taken together, these results indicate that lipid peroxidation and evidence suggestive of ferroptosis occurs during ATB-DILI, and glutathione replenishment prevents this process while iron supplementation augmenting this effect.

Topics: Animals; Antitubercular Agents; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Drug Therapy, Combination; Ferroptosis; Glutathione; Humans; Iron; Isoniazid; Lipid Peroxidation; Liver; Male; Mice; Mice, Inbred C57BL; Microscopy, Electron, Transmission; Reactive Oxygen Species; Rifampin

Phenyl- and bioisosteric ferrocenyl-derived aminoquinoline-benzimidazole hybrid compounds were synthesised and evaluated for their in vitro antiplasmodial activity against the chloroquine-sensitive NF54 and multi-drug resistant K1 strains of the human malaria parasite, Plasmodium falciparum. All compounds were active against the two strains, generally showing enhanced activity in the K1 strain, with resistance indices less than 1. Cytotoxicity studies using Chinese hamster ovarian cells revealed that the hybrids were relatively non-cytotoxic and demonstrated selective killing of the parasite. Based on favourable in vitro antiplasmodial and cytotoxicity data, the most active phenyl (4c) and ferrocenyl (5b) hybrids were tested in vivo against the rodent Plasmodium berghei mouse model. Both compounds caused a reduction in parasitemia relative to the control, with 5c displaying superior activity (92% reduction in parasitemia at 4 × 50 mg/kg oral doses). The most active phenyl and ferrocenyl derivatives showed inhibition of β-haematin formation in a NP-40 detergent-mediated assay, indicating a possible contributing mechanism of antiplasmodial action. The most active ferrocenyl hybrid did not display appreciable reactive oxygen species (ROS) generation in a ROS-induced DNA cleavage gel electrophoresis study. The compounds were also screened for their in vitro activity against Mycobacterium tuberculosis. The hybrids containing a more hydrophobic substituent had enhanced activity (<32.7 μM) compared to those with a less hydrophobic substituent (>62.5 μM).

Topics: Animals; Anti-Bacterial Agents; Antimalarials; Benzimidazoles; Disease Models, Animal; Dose-Response Relationship, Drug; Ferrous Compounds; Malaria; Mice; Molecular Structure; Mycobacterium tuberculosis; Parasitic Sensitivity Tests; Plasmodium falciparum; Quinolines; Structure-Activity Relationship

Staphylococcus aureus can cause persistent infections and is known to develop persister cells in vitro. However, the in vivo significance of in vitro persisters in general is largely unclear. Here, we evaluated S. aureus stationary phase cultures and biofilm bacteria enriched in persister bacteria in comparison with actively growing log phase bacteria in terms of their ability to cause disease in a mouse skin infection model. We found that mice infected with the stationary phase and biofilm bacteria, which were enriched with persisters, produced more pronounced skin lesions that took longer to heal, and had more severe skin pathology and higher bacterial load than mice infected with log phase bacteria. Using our persistent infection mouse model, we showed that the clinically recommended treatment for recurrent S. aureus skin infection, doxycycline + rifampin, was not effective in eradicating the bacteria in mice. Analogous findings were observed in a Caenorhabditis elegans model, where stationary phase S. aureus caused greater virulence or mortality than log phase bacteria as early as two days post-infection. Our findings associate in vitro persisters and biofilm bacteria with more persistent and more severe infections and emphasize the importance of quality or metabolic status of the inoculum bacteria (persister bacteria versus growing bacteria) not just the number of bacteria in causing disease. The persistent infection mouse model we developed with persister inocula should have implications for understanding the process of disease establishment and pathogenesis, for developing persistent infection animal models, and for developing more effective treatments for chronic persistent infections in general.

Topics: Animals; Biofilms; Caenorhabditis elegans; Disease Models, Animal; Doxycycline; Female; Mice; Rifampin; Staphylococcal Skin Infections; Staphylococcus aureus

Topics: Animals; Anti-Bacterial Agents; Cornea; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Synergism; Drug Therapy, Combination; Eye Infections, Bacterial; Female; Humans; Keratitis; Mice; Mice, Inbred BALB C; Moxifloxacin; Ophthalmic Solutions; Polymyxin B; Pseudomonas aeruginosa; Pseudomonas Infections; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome; Trimethoprim

Rifampin (RIF) plus clarithromycin (CLR) for 8 weeks is now the standard of care for Buruli ulcer (BU) treatment, but CLR may not be an ideal companion for rifamycins due to bidirectional drug-drug interactions. The oxazolidinone linezolid (LZD) was previously shown to be active against

Topics: Animals; Anti-Bacterial Agents; Buruli Ulcer; Clarithromycin; Disease Models, Animal; Female; Linezolid; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Oxazolidinones; Rifampin; Tetrazoles

Current treatments for tuberculosis (TB) are effective in controlling Mycobacterium tuberculosis (Mtb) growth, yet have significant side effects and do not prevent reinfection. Therefore, it is critical to understand why our host defense system is unable to generate permanent immunity to Mtb despite prolonged anti-tuberculosis therapy (ATT). Here, we demonstrate that treatment of mice with the most widely used anti-TB drugs, rifampicin (RIF) or isoniazid (INH) and pyrazinamide (PYZ), significantly altered the composition of the gut microbiota. Unexpectedly, treatment of mice with the pro-Mtb drugs INH and PYZ, but not RIF, prior to Mtb infection resulted in an increased bacterial burden, an effect that was reversible by fecal transplantation from untreated animals. Mechanistically, susceptibility of INH/PYZ-treated mice was associated with impaired metabolism of alveolar macrophages and defective bactericidal activity. Collectively, these data indicate that dysbiosis induced by ATT administered to millions of individuals worldwide may have adverse effects on the anti-Mtb response of alveolar macrophages.

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Drug-Related Side Effects and Adverse Reactions; Dysbiosis; Gastrointestinal Microbiome; Host-Pathogen Interactions; Humans; Immunity, Innate; Immunomodulation; Isoniazid; Macrophages, Alveolar; Mice; Mice, Inbred C57BL; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Tuberculosis, Pulmonary

Mycobacterium tuberculosis, the etiologic agent of tuberculosis, is an intracellular pathogen of alveolar macrophages. These cells avidly take up nanoparticles, even without the use of specific targeting ligands, making the use of nanotherapeutics ideal for the treatment of such infections. Methoxy poly(ethylene oxide)- block-poly(ε-caprolactone) nanoparticles of several different polymer blocks' molecular weights and sizes (20-110 nm) were developed and critically compared as carriers for rifampicin, a cornerstone in tuberculosis therapy. The polymeric nanoparticles' uptake, consequent organelle targeting and intracellular degradation were shown to be highly dependent on the nanoparticles' physicochemical properties (the cell uptake half-lives 2.4-21 min, the degradation half-lives 51.6 min-ca. 20 h after the internalization). We show that the nanoparticles are efficiently taken up by macrophages and are able to effectively neutralize the persisting bacilli. Finally, we demonstrate, using a zebrafish model of tuberculosis, that the nanoparticles are well tolerated, have a curative effect, and are significantly more efficient compared to a free form of rifampicin. Hence, these findings demonstrate that this system shows great promise, both in vitro and in vivo, for the treatment of tuberculosis.

Topics: Animals; Disease Models, Animal; Drug Carriers; Humans; Macrophages; Mice; Mycobacterium tuberculosis; Nanoparticles; RAW 264.7 Cells; Rifampin; Tuberculosis; Zebrafish

In vivo bioluminescence imaging (BLI) provides noninvasive monitoring of bacterial burden in animal models of orthopaedic implant-associated infection (OIAI). However, technical limitations have limited its use to mouse and rat models of OIAI. The goal of this study was to develop a larger, rabbit model of OIAI using in vivo BLI to evaluate the efficacy of an antibiotic-releasing implant coating.. A nanofiber coating loaded with or without linezolid-rifampin was electrospun onto a surgical-grade locking peg. To model OIAI in rabbits, a medial parapatellar arthrotomy was performed to ream the femoral canal, and a bright bioluminescent methicillin-resistant Staphylococcus aureus (MRSA) strain was inoculated into the canal, followed by retrograde insertion of the coated implant flush with the articular surface. In vivo BLI signals were confirmed by ex vivo colony-forming units (CFUs) from tissue, bone, and implant specimens.. In this rabbit model of OIAI (n = 6 rabbits per group), implants coated without antibiotics were associated with significantly increased knee width and in vivo BLI signals compared with implants coated with linezolid-rifampin (p < 0.001 and p < 0.05, respectively). On day 7, the implants without antibiotics were associated with significantly increased CFUs from tissue (mean [and standard error of the mean], 1.4 × 10 ± 2.1 × 10 CFUs; p < 0.001), bone (6.9 × 10 ± 3.1 × 10 CFUs; p < 0.05), and implant (5.1 × 10 ± 2.2 × 10 CFUs; p < 0.05) specimens compared with implants with linezolid-rifampin, which demonstrated no detectable CFUs from any source.. By combining a bright bioluminescent MRSA strain with modified techniques, in vivo BLI in a rabbit model of OIAI demonstrated the efficacy of an antibiotic-releasing coating.. The new capability of in vivo BLI for noninvasive monitoring of bacterial burden in larger-animal models of OIAI may have important preclinical relevance.

Topics: Analysis of Variance; Animals; Anti-Bacterial Agents; Delayed-Action Preparations; Disease Models, Animal; Drug Combinations; Linezolid; Luminescent Measurements; Male; Methicillin-Resistant Staphylococcus aureus; Prosthesis-Related Infections; Rabbits; Rifampin; Staphylococcal Infections

Clofazimine and high-dose rifapentine have each separately been associated with treatment-shortening activity when incorporated into tuberculosis (TB) treatment regimens. We hypothesized that both modifications, i.e., the addition of clofazimine and the replacement of rifampin with high-dose rifapentine, in the first-line regimen for drug-susceptible TB would significantly shorten the duration of treatment necessary for cure. We tested this hypothesis in a well-established BALB/c mouse model of TB chemotherapy and also in a C3HeB/FeJ mouse model in which mice can develop caseous necrotic lesions, an environment where rifapentine and clofazimine may individually be less effective. In both mouse models, replacing rifampin with high-dose rifapentine and adding clofazimine in the first-line regimen resulted in greater bactericidal and sterilizing activity than either modification alone, suggesting that a rifapentine- and clofazimine-containing regimen may have the potential to significantly shorten the treatment duration for drug-susceptible TB. These data provide preclinical evidence supporting the evaluation of regimens combining high-dose rifapentine and clofazimine in clinical trials.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Clofazimine; Disease Models, Animal; Drug Administration Schedule; Drug Therapy, Combination; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Rifampin; Tuberculosis

Topics: Animals; Anti-Bacterial Agents; Bacterial Load; Buruli Ulcer; Clarithromycin; Clofazimine; Disease Models, Animal; Drug Resistance, Bacterial; Drug Therapy, Combination; Electron Transport; Humans; Imidazoles; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mycobacterium ulcerans; Piperidines; Pyridines; Rifampin; Streptomycin

The aim of this study was to investigate the antibacterial activity of a synthetic aryl isonitrile compound (35) that was developed as part of a compound library to identify new antibacterial agents effective against methicillin-resistant Staphylococcus aureus (MRSA).. Compound 35 was evaluated against MRSA isolates by the broth microdilution assay and for toxicity to mammalian keratinocytes using the MTS assay. A multistep resistance selection assay was conducted to investigate MRSA resistance development to 35. A Caco-2 bidirectional permeability assay was employed to evaluate the ability of 35 to permeate across the gastrointestinal tract, and compound 35 was incubated with human liver microsomes to determine susceptibility to hepatic metabolism. Finally, compound 35 was evaluated in an uncomplicated MRSA skin infection mouse model and an MRSA neutropenic thigh infection mouse model.. Compound 35 inhibited the growth of MRSA clinical isolates at 2-4μM and was non-toxic to human keratinocytes. No resistance formation was observed with MRSA against compound 35 after 10 serial passages. In a murine skin wound model, compound 35 significantly reduced the burden of MRSA, similar to the antibiotic fusidic acid. Compound 35 exhibited a marked improvement both in permeability and stability to hepatic metabolism (half-life >11h) relative to the first-generation lead compound. In a neutropenic thigh infection mouse model, compound 35 successfully reduced the burden of MRSA in immunocompromised mice.. In summary, compound 35 was identified as a new lead aryl isonitrile compound that warrants further investigation as a novel antibacterial agent.

Topics: Animals; Anti-Bacterial Agents; Caco-2 Cells; Disease Models, Animal; Female; Fusidic Acid; Humans; Keratinocytes; Male; Methicillin-Resistant Staphylococcus aureus; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Microsomes, Liver; Nitriles; Rifampin; Skin; Staphylococcal Infections; Staphylococcal Skin Infections

External ventricular drainage (EVD) carries a high risk of ventriculitis, increasingly caused by MDR Gram-negative bacteria such as Escherichia coli and Acinetobacter baumannii. Existing antimicrobial EVD catheters are not effective against these, and we have developed a catheter with activity against MDR bacteria and demonstrated the safety of the new formulation for use in the brain.. Our aim was to determine the ability of a newly formulated impregnated EVD catheters to withstand challenge with MDR Gram-negative bacteria and to obtain information about its safety for use in the CNS.. Catheters impregnated with three antimicrobials (rifampicin, trimethoprim and triclosan) were challenged in flow conditions at four weekly timepoints with high doses of MDR bacteria, including MRSA and Acinetobacter, and monitored for bacterial colonization. Catheter segments were also inserted intracerebrally into Wistar rats, which were monitored for clinical and behavioural change, and weight loss. Brains were removed after either 1 week or 4 weeks, and examined for evidence of inflammation and toxicity.. Control catheters colonized quickly after the first challenge, while no colonization occurred in the impregnated catheters even after the 4 week challenge. Animals receiving the antimicrobial segments behaved normally and gained weight as expected. Neurohistochemistry revealed only surgical trauma and no evidence of neurotoxicity.. The antimicrobial catheter appears to withstand bacterial challenge for at least 4 weeks, suggesting that it might offer protection against infection with MDR Gram-negative bacteria in patients undergoing EVD. It also appears to be safe for use in the CNS.

Topics: Animals; Anti-Bacterial Agents; Bacterial Infections; Catheter-Related Infections; Catheterization; Catheters; Cerebral Ventriculitis; Cerebrospinal Fluid Leak; Disease Models, Animal; Humans; Male; Models, Theoretical; Rats, Wistar; Rifampin; Treatment Outcome; Triclosan; Trimethoprim

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) infections represent a major therapeutic problem and combination therapy may be the chemotherapeutic option.. Bioluminescent CRPA was developed through sequential subcultures in subinhibitory concentrations of meropenem from an engineered strain of bioluminescent PA Xen5. Then CRPA was injected intraperitoneally to establish an intraperitoneal murine infection model. Treatments of colistin alone or combined with rifampicin or meropenem were started 1 h after infection. In vivo bioluminescence imaging was applied dynamically at 0 h, and 2 and 5 h after treatment. Ex vivo bacterial counts from liver, kidney, spleen, lung and blood samples were also determined 5 h after treatment.. In vivo imaging showed that both low- and high-dose colistin combined with rifampicin resulted in a significant decrease in bioluminescence signals compared with monotherapy of colistin or rifampicin alone, whereas colistin and meropenem combination therapy did not show a greater bactericidal effect compared with monotherapy. Ex vivo bacterial count results also confirmed that combination of both low- and high-dose colistin with rifampicin resulted in significantly reduced colony counts from five kinds of tissue samples. However, only combination of high-dose colistin + meropenem resulted in reduced colony counts merely in lung and blood samples.. Compared with single drugs, colistin and rifampicin combination therapy could exert synergistic effects, which might provide a better alternative when treating CRPA infections in clinical practice. Combination of colistin and meropenem should be considered with caution because it barely shows any synergism in the present in vivo model.

Topics: Animal Structures; Animals; Anti-Bacterial Agents; Bacterial Load; beta-Lactam Resistance; Colistin; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Female; Intraabdominal Infections; Luminescent Measurements; Meropenem; Mice, Inbred BALB C; Pseudomonas aeruginosa; Pseudomonas Infections; Rifampin; Staining and Labeling; Treatment Outcome

Although high-dose rifampicin holds promise for improving tuberculosis disease control by eradication of persistent bacteria, the optimal dose of rifampicin that kills persistent bacteria and shortens the treatment duration is unknown.. The Cornell mouse model was used to test the efficacy of rifampicin at elevated doses combined with isoniazid and pyrazinamide to kill actively growing and persistent bacilli and to measure relapse rate. Persistent bacteria were evaluated using Mycobacterium tuberculosis culture supernatant containing resuscitation-promoting factors. Pharmacokinetic parameters and dose-dependent activity for cultivable and persistent bacilli were determined.. Increasing doses of rifampicin in combination with isoniazid and pyrazinamide resulted in dose-dependent faster bacterial clearance. Evaluated both on solid media and in culture filtrate containing resuscitation-promoting factors, a regimen containing a standard dose of rifampicin at 10 mg/kg over 14 weeks failed to achieve organ sterility. In contrast, higher doses of rifampicin achieved organ sterility in a much shorter time of 8-11 weeks. Disease relapse, which occurred in 86% of mice treated with the standard regimen for 14 weeks, was completely prevented by rifampicin doses of ≥ 30 mg/kg.. In the treatment of murine tuberculosis, a rifampicin dose of 30 mg/kg was sufficient to eradicate persistent M. tuberculosis, allowing shorter treatment duration without disease relapse.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Female; Isoniazid; Lung; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Recurrence; Rifampin; Spleen; Tuberculosis

The treatment of drug-susceptible tuberculosis (TB) is long and cumbersome. Mismanagement of TB treatment can lead to the emergence of drug resistance in patients, so shortening the treatment duration could significantly improve TB chemotherapy and prevent the development of drug resistance. We previously discovered that high concentrations of vitamin C sterilize cultures of drug-susceptible and drug-resistant

Topics: Animals; Antitubercular Agents; Ascorbic Acid; Disease Models, Animal; Drug Resistance, Bacterial; Drug Synergism; Drug Therapy, Combination; Female; Humans; Injections, Intraperitoneal; Isoniazid; Lung; Mice; Mice, Inbred CBA; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Rifampin; Treatment Outcome; Tuberculosis, Multidrug-Resistant

Filarial parasites can be targeted by antibiotic treatment due to their unique endosymbiotic relationship with Wolbachia bacteria. This finding has led to successful treatment strategies in both, human onchocerciasis and lymphatic filariasis. A 4-6 week treatment course using doxycycline results in long-term sterility and safe macrofilaricidal activity in humans. However, current treatment times and doxycycline contraindications in children and pregnant women preclude widespread administration of doxycycline in public health control programs; therefore, the search for shorter anti-wolbachial regimens is a focus of ongoing research. We have established an in vivo model for compound screening, using mice infected with Litomosoides sigmodontis. We could show that gold standard doxycycline treatment did not only deplete Wolbachia, it also resulted in a larval arrest. In this model, combinations of registered antibiotics were tested for their anti-wolbachial activity. Administration of rifamycins in combination with doxycycline for 7 days successfully depleted Wolbachia by > 2 log (>99% reduction) and thus resulted in a significant reduction of the treatment duration. Using a triple combination of a tetracycline (doxycycline or minocycline), a rifamycin and a fluoroquinolone (moxifloxacin) led to an even greater shortening of the treatment time. Testing all double combinations that could be derived from the triple combinations revealed that the combination of rifapentine (15mg/kg) and moxifloxacin (2 x 200mg/kg) showed the strongest reduction of treatment time in intraperitoneal and also oral administration routes. The rifapentine plus moxifloxacin combination was equivalent to the triple combination with additional doxycycline (>99% Wolbachia reduction). These investigations suggest that it is possible to shorten anti-wolbachial treatment times with combination treatments in order to achieve the target product profile (TPP) requirements for macrofilaricidal drugs of no more than 7-10 days of treatment.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Therapy, Combination; Filariasis; Filarioidea; Fluoroquinolones; Mice; Moxifloxacin; Rifampin; Tetracyclines; Time Factors; Treatment Outcome; Wolbachia

To evaluate the suitability of Galleria mellonella larvae as an in vivo model and drug-screening tool for mycobacteria infections.. Larvae were infected using a range of inoculum sizes from a variety of rapid-growing mycobacteria, including strains of M. fortuitum, M. marinum and M. aurum. Larval survival, internal bacterial burden and the effects of amikacin, ciprofloxacin, ethambutol, isoniazid and rifampicin treatment on larval survival were measured over 144 h. The effects of these anti-mycobacterial drugs on phagocytosis and circulating haemocyte numbers were also examined using microscopy.. Larval survival decreased after infection with M. fortuitum and M. marinum in a dose-dependent manner, but remained unaffected by M. aurum. Heat-killed bacteria did not cause larval death. Where antibiotic monotherapy was efficacious, larval survival post-infection increased in a dose-dependent fashion. However, efficacy varied between different antibiotics and species of infecting mycobacteria and, apart from rifampicin, efficacy in vivo correlated poorly with the in vitro minimum inhibitory concentrations (MICs). Combinations of antibiotics led to higher survival of infected larvae than antibiotic monotherapy. Selected antibiotic treatments that enhanced larval survival reduced the overall internal burden of infecting mycobacteria, but did not eradicate the pathogens. Administration of amikacin or ethambutol to uninfected larvae induced an initial transient increase in the numbers of circulating haemocytes and reduced the phagocytic rate of haemocytes in larvae infected with M. marinum.. This report demonstrates the potential of employing a wax moth larvae model for studying fast-growing mycobacteria infections, and as a cheap, effective system for initial screening of novel treatments.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Humans; Moths; Mycobacterium Infections, Nontuberculous; Nontuberculous Mycobacteria; Rifampin

Preclinical treatment outcome evaluation of tuberculosis (TB) occurs primarily in mice. Current designs compare relapse rates of different regimens at selected time points, but lack information about the correlation between treatment length and treatment outcome, which is required to efficiently estimate a regimens' treatment-shortening potential. Therefore we developed a new approach. BALB/c mice were infected with a Mycobacterium tuberculosis Beijing genotype strain and were treated with rifapentine-pyrazinamide-isoniazid-ethambutol (R

Topics: Administration, Oral; Animals; Antitubercular Agents; Disease Models, Animal; Drug Therapy, Combination; Ethambutol; Female; Genotype; Humans; Mice; Mice, Inbred BALB C; Models, Theoretical; Moxifloxacin; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Treatment Outcome; Tuberculosis

Topics: Animals; Antibiotics, Antitubercular; Bacterial Load; Clinical Trials, Phase II as Topic; Computer Simulation; Disease Models, Animal; Dose-Response Relationship, Drug; Humans; Mice; Microbial Sensitivity Tests; Models, Biological; Mycobacterium tuberculosis; Rifampin; Translational Research, Biomedical; Treatment Outcome; Tuberculosis, Pulmonary

Open fractures become infected despite meticulous debridement and care. Locally applied antibiotics, commonly embedded in polymethylmethacrylate, deliver high doses of drug directly to the fracture site. Direct application of antibiotic powder, which is being applied prophylactically in spine surgery, is a recent interest in the trauma sector, where bacterial biofilms are more prevalent. Traditional antibiotics, such as vancomycin, are poor performers against bacterial biofilms thus are ineffective in delayed treatment. Rifampin is an effective eradicator of Staphylococcal biofilms. Here, a rat model of musculoskeletal trauma was used to evaluate the utility of locally applied rifampin powder for reducing established orthopedic Staphylococcal infections in a delayed treatment scenario that previously indicated the limited use of local vancomycin. By applying rifampin powder directly to the contaminated segmental defect, the number of bacteria, as well as clinical indications of infection, were significantly reduced compared to vancomycin and daptomycin. Considering the Infectious Disease Society of America's recommendation to use rifampin in combination with another antibiotic to reduce the onset of rifampin resistance, rifampin powder was also applied in combination with vancomycin or daptomycin with insignificant changes in eradication performance. No indications of rifampin resistance were identified. Clinical Significance: The use of locally applied rifampin is a promising therapy for mature and tolerant musculoskeletal infections. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. J Orthop Res 36:3136-3141, 2018.

Topics: Administration, Topical; Animals; Anti-Bacterial Agents; Biofilms; Disease Models, Animal; Musculoskeletal System; Polymethyl Methacrylate; Powders; Rats; Rats, Inbred Lew; Rifampin; Staphylococcal Infections; Time-to-Treatment; Vancomycin

Host directed immunomodulation represents potential new adjuvant therapies in infectious diseases such as tuberculosis. Major cytokines like TNFα exert a multifold role in host control of mycobacterial infections. GM-CSF and its receptor are over-expressed during acute M. tuberculosis infection and we asked how GM-CSF neutralization might affect host response, both in immunocompetent and in immunocompromised TNFα-deficient mice. GM-CSF neutralizing antibodies, at a dose effectively preventing acute lung inflammation, did not affect M. tuberculosis bacterial burden, but increased the number of granuloma in wild-type mice. We next assessed whether GM-CSF neutralization might affect the control of M. tuberculosis by isoniazid/rifampicin chemotherapy. GM-CSF neutralization compromised the bacterial control under sub-optimal isoniazid/rifampicin treatment in TNFα-deficient mice, leading to exacerbated lung inflammation with necrotic granulomatous structures and high numbers of intracellular M. tuberculosis bacilli. In vitro, GM-CSF neutralization promoted M2 anti-inflammatory phenotype in M. bovis BCG infected macrophages, with reduced mycobactericidal NO production and higher intracellular M. bovis BCG burden. Thus, GM-CSF pathway overexpression during acute M. tuberculosis infection contributes to an efficient M1 response, and interfering with GM-CSF pathway in the course of infection may impair the host inflammatory response against M. tuberculosis.

Topics: Animals; Antibodies, Neutralizing; Antitubercular Agents; Cattle; Disease Models, Animal; Granulocyte-Macrophage Colony-Stimulating Factor; Immunologic Factors; Immunomodulation; Isoniazid; Macrophages; Mice; Mycobacterium bovis; Mycobacterium tuberculosis; Rifampin; Treatment Outcome; Tuberculosis, Pulmonary

The chloramphenicol/florfenicol resistance gene cfr, which mediates cross-resistance to linezolid and other classes of antimicrobial agents, represents a global therapeutic challenge due to its dissemination among MDR nosocomial pathogens, including MRSA. This study aimed to compare the efficacy of the linezolid/rifampicin combination in a murine pneumonia model caused by cfr-positive and cfr-negative clinical MRSA strains.. Synergistic activity between linezolid and rifampicin was evaluated by chequerboard and time-kill assays. Pharmacokinetic profiles in plasma and epithelial lining fluid (ELF) as well as the therapeutic efficacy of linezolid alone and in combination with rifampicin were investigated in a murine pneumonia model. The Emax Hill equation was used to model the dose-response relationship.. Increased susceptibility of the study MRSA strains to linezolid was observed with the rifampicin combination (MIC decreased 2- to 16-fold versus linezolid alone). The combination had synergistic activity (fractional inhibitory concentration index ≤0.5) against all cfr-positive MRSA isolates. Linezolid demonstrated excellent pulmonary penetration with an ELF/fplasma AUC ratio of 2.68 ± 0.17. The addition of rifampicin significantly improved the efficacy of linezolid in the pneumonia model due to cfr-positive and cfr-negative MRSA strains. The fAUC/MIC targets of linezolid associated with stasis, 1 log10 kill and 2 log10 kill were 15.9, 38.8 and 175 in plasma, and 43.5, 108 and 415 in ELF, respectively. Importantly, the linezolid fAUC/MIC targets in both plasma and ELF were 2.4-6.7 times lower in combined linezolid/rifampicin therapy versus linezolid monotherapy (P < 0.005).. Combination of linezolid with rifampicin significantly improved the efficacy of linezolid in the murine pneumonia model caused by MRSA strains in the presence and absence of the cfr gene.

Topics: Animals; Anti-Bacterial Agents; Bacterial Proteins; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Female; Linezolid; Methicillin-Resistant Staphylococcus aureus; Mice; Mice, Inbred ICR; Microbial Sensitivity Tests; Pneumonia, Bacterial; Rifampin; Specific Pathogen-Free Organisms; Staphylococcal Infections

New therapeutic strategies are needed to treat drug resistant tuberculosis (TB) and to improve treatment for drug sensitive TB. Pyrazinamide (PZA) is a critical component of current first-line TB therapy. However, the rise in PZA-resistant TB cases jeopardizes the future utility of PZA. To address this problem, we used the guinea pig model of TB and tested the efficacy of an inhaled dry powder combination, referred to as Pyrazinoic acid/ester Dry Powder (PDP), which is comprised of pyrazinoic acid (POA), the active moiety of PZA, and pyrazinoic acid ester (PAE), which is a PZA analog. Both POA and PAE have the advantage of being able to act on PZA-resistant Mycobacterium tuberculosis. When used in combination with oral rifampicin (R), inhaled PDP had striking effects on tissue pathology. Effects were observed in lungs, the site of delivery, but also in the spleen and liver indicating both local and systemic effects of inhaled PDP. Tissue granulomas that harbor M. tuberculosis in a persistent state are a hallmark of TB and they pose a challenge for therapy. Compared to other treatments, which preferentially cleared non-necrotic granulomas, R+PDP reduced necrotic granulomas more effectively. The increased ability of R+PDP to act on more recalcitrant necrotic granulomas suggests a novel mechanism of action. The results presented in this report reveal the potential for developing therapies involving POA that are optimized to target necrotic as well as non-necrotic granulomas as a means of achieving more complete sterilization of M. tuberculosis bacilli and preventing disease relapse when therapy ends.

Topics: Aerosols; Animals; Antitubercular Agents; Bacterial Load; Disease Models, Animal; Drug Therapy, Combination; Dry Powder Inhalers; Granuloma, Respiratory Tract; Guinea Pigs; Male; Mycobacterium tuberculosis; Necrosis; Pyrazinamide; Respiratory Tract Absorption; Rifampin; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary

Topics: Adjuvants, Immunologic; Adult; Animals; Bacterial Vaccines; Child; Communicable Diseases, Emerging; Disease Models, Animal; Humans; Immunotherapy; Leprostatic Agents; Leprosy; Mycobacterium leprae; Neglected Diseases; Post-Exposure Prophylaxis; Rifampin; Vaccines, Synthetic

Mycobacterium ulcerans is the causative agent of Buruli ulcer, a neglected tropical skin disease that is most commonly found in children from West and Central Africa. Despite the severity of the infection, therapeutic options are limited to antibiotics with severe side effects. Here, we show that M. ulcerans is susceptible to the anti-tubercular drug Q203 and related compounds targeting the respiratory cytochrome bc

Topics: Africa; Animals; Antibiotics, Antitubercular; Australia; Buruli Ulcer; Disease Models, Animal; Electron Transport Complex III; Electron Transport Complex IV; Female; Humans; Imidazoles; Inhibitory Concentration 50; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Neglected Diseases; Piperidines; Pyridines; Rifampin; Treatment Outcome

We hypothesized that an in vitro, stretch-based model of neural injury may be useful to identify compounds that decrease the cellular damage in neurotrauma.. We screened three neural cell lines (B35, RN33B and SH-SY5Y) subjected to two differentiation methods and selected all-trans-retinoic acid-differentiated B35 rat neuroblastoma cells subjected to rapid stretch injury, coupled with a subthreshold concentration of H. From screening of a composite library of 3500 drugs, five drugs (when applied in a post-treatment regimen relative to stretch injury) improved both LDH and MTT responses. The effects of rifampicin were investigated in further detail. Rifampicin reduced cell necrosis and apoptosis and improved cellular bioenergetics. In a second model (stretch injury in human stem cell-derived neurons), rifampicin pretreatment attenuated LDH release, protected against the loss of neurite length and maintained neuron-specific class III β-tubulin immunoreactivity.. We conclude that the current model is suitable for medium-throughput screening to identify compounds with neuroprotective potential. Rifampicin, when applied either in pre- or post-treatment, improves the viability of neurons subjected to stretch injury and protects against neurite loss. Rifampicin may be a candidate for repurposing for the therapy of traumatic brain injury.. This article is part of a themed section on Inventing New Therapies Without Reinventing the Wheel: The Power of Drug Repurposing. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.2/issuetoc.

Topics: Animals; Apoptosis; Brain Injuries, Traumatic; Cell Death; Cell Line, Tumor; Disease Models, Animal; Drug Evaluation, Preclinical; Humans; Hydrogen Peroxide; L-Lactate Dehydrogenase; Mitochondria; Neuroprotective Agents; Rifampin; Stress, Mechanical; Tetrazolium Salts

A series of pyrazolo[1,5-a]pyridine-3-carboxamide hybrids were designed and evaluated as novel anti-tubercular agents. The representative hybrid 7 exhibited promising in vitro activity against susceptive strain H37Rv and a panel of drug-resistant Mtb strains with MIC values of 0.006 μg/mL and ranged from 0.003 to 0.014 μg/mL, respectively. More importantly, the hybrid 7 also showed very low cytotoxicity, and could significantly reduce the mycobacterial burden in a mouse model infected with autoluminescent H37Ra strain, which may serve as a lead compound for further development of new anti-tubercular agents.

Topics: Animals; Antitubercular Agents; Cell Death; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Resistance, Microbial; Mice; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Pyridines

The medical treatment of periprosthetic joint infection (PJI) involves prolonged systemic antibiotic courses, often with suboptimal clinical outcomes including increased morbidity and health-care costs. Oral and intravenous monotherapies and combination antibiotic regimens were evaluated in a mouse model of methicillin-resistant Staphylococcus aureus (MRSA) PJI.. Oral linezolid with or without oral rifampin, intravenous vancomycin with oral rifampin, intravenous daptomycin or ceftaroline with or without oral rifampin, oral doxycycline, or sham treatment were administered at human-exposure doses for 6 weeks in a mouse model of PJI. Bacterial burden was assessed by in vivo bioluminescent imaging and ex vivo counting of colony-forming units (CFUs), and reactive bone changes were evaluated with radiographs and micro-computed tomography (μCT) imaging.. Oral-only linezolid-rifampin and all intravenous antibiotic-rifampin combinations resulted in no recoverable bacteria and minimized reactive bone changes. Although oral linezolid was the most effective monotherapy, all oral and intravenous antibiotic monotherapies failed to clear infection or prevent reactive bone changes.. Combination antibiotic-rifampin regimens, including oral-only linezolid-rifampin and the newer ceftaroline-rifampin combinations, were highly effective and more efficacious than monotherapies when used against a preclinical MRSA PJI.. This study provides important preclinical evidence to better optimize future antibiotic therapy against PJIs. In particular, the oral-only linezolid-rifampin option might reduce venous access complications and health-care costs.

Topics: Administration, Oral; Animals; Anti-Bacterial Agents; Ceftaroline; Cephalosporins; Daptomycin; Disease Models, Animal; Doxycycline; Drug Combinations; Linezolid; Methicillin-Resistant Staphylococcus aureus; Mice; Prosthesis-Related Infections; Rifampin; Staphylococcal Infections; Treatment Outcome

Preliminary preclinical and observational studies suggest the potential utility of metformin as an adjunctive, host-directed agent for treatment of tuberculosis (TB). In this study, we sought to investigate the bactericidal and sterilizing activities of human-like exposures of metformin when given in combination with the first-line regimen against chronic tuberculosis in BALB/c mice. Mice receiving metformin adjunctive therapy had similar lung bacillary burdens with control mice during treatment, and the proportion of mice with microbiological relapse was similar between the two groups.

Topics: Animals; Antitubercular Agents; Bacterial Load; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Female; Isoniazid; Lung; Metformin; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Recurrence; Rifampin; Tuberculosis, Pulmonary

Biapenem, a carbapenem antibiotic, has been shown to have synergistic bactericidal anti-TB activity when combined with rifampicin both in vitro and in the mouse model of TB chemotherapy. We hypothesized that this synergy would result in biapenem/rifampicin activity against rifampicin-resistant Mycobacterium tuberculosis .. Our objective was to evaluate the synergy of biapenem/rifampicin against both low- and high-level rifampicin-resistant strains of M. tuberculosis , in vitro and in the mouse model.. Biapenem/rifampicin activity was evaluated using three strains of M. tuberculosis : strain 115R (low-level rifampicin resistance); strain 124R (high-level rifampicin resistance); and the drug-susceptible H37Rv parent strain. Biapenem/rifampicin synergy was evaluated in vitro by chequerboard titration. In vivo , we first conducted a dose-ranging experiment with biapenem against H37Rv in the mouse model. We then evaluated biapenem/rifampicin activity in mice infected with each M. tuberculosis strain.. In vitro , synergy was observed between biapenem and rifampicin against H37Rv and strain 115R. In vivo , biapenem exhibited clear dose-dependent activity against H37Rv, with all biapenem doses as active or more active than rifampicin alone. Biapenem and rifampicin had synergistic bactericidal activity against H37Rv in the mouse model; no synergy was observed in mice infected with either of the rifampicin-resistant strains. Biapenem alone was active against all three strains.. Our preclinical experiments indicate that biapenem has potential for use as an anti-TB drug, including for use against rifampicin-resistant TB. Thus, biapenem has promise for repurposing as a 'new' - and desperately needed - drug for the treatment of drug-resistant TB.

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Drug Resistance, Bacterial; Drug Synergism; Female; Mice, Inbred BALB C; Microbial Viability; Mycobacterium tuberculosis; Rifampin; Thienamycins; Treatment Outcome; Tuberculosis

The aim of the study is to compare counting of colony forming units (CFU), the time to positivity (TTP) assay and the molecular bacterial load (MBL) assay, and explore whether the last assays can detect a subpopulation which is unable to grown on solid media. CFU counting, TTP and the MBL assay were used to determine the mycobacterial load in matched lung samples of a murine tuberculosis model. Mice were treated for 24 weeks with 4 treatment arms: isoniazid (H) - rifampicin (R) - pyrazinamide (Z), HRZ-Streptomycin (S), HRZ - ethambutol (E) or ZES. Inverse relationships were observed when comparing TPP with CFU or MBL. Positive associations were observed when comparing CFU with MBL. Description of the net elimination of bacteria was performed for CFU vs. time, MBL vs. time and 1/TTP vs. time and fitted by nonlinear regression. CFU vs. time and 1/TTP vs. time showed bi-phasic declines with the exception of HRZE. A similar rank order, based on the alpha slope, was found comparing CFU vs. time and TTP vs. time, respectively HRZE, HRZ, HRZS and ZES. In contrast, MBL vs. time showed a mono-phasic decline with a flat gradient of elimination and a different rank order respectively, ZES, HRZ, HRZE and HRZS. The correlations found between methods reflects the ability of each to discern the general mycobacterial load. Based on the description of net elimination, we conclude that the MBL assay can detect a subpopulation of Mycobacterium tuberculosis which is not detected by the CFU or TTP assays.

Topics: Animals; Antitubercular Agents; Bacterial Load; Colony Count, Microbial; Disease Models, Animal; DNA, Bacterial; Ethambutol; Female; Isoniazid; Lung; Mice, Inbred BALB C; Mycobacterium tuberculosis; Nonlinear Dynamics; Predictive Value of Tests; Pyrazinamide; Ribotyping; Rifampin; RNA, Ribosomal, 16S; Streptomycin; Time Factors; Tuberculosis, Pulmonary

Bone-like hydroxyapatite/poly amino acid (BHA/PAA) is a potential bone repair material. Rifapentine-loaded poly(lactic‑co‑glycolic acid) microspheres (RPMs) are bioactive and efficient controlled‑release delivery systems used in vitro. The aim of the present study was to investigate the in vivo drug release characteristics of RPM‑loaded BHA/PAA on a rabbit model of bone defect. RPM was combined with BHA/PAA to obtain the drug‑loaded, slow‑releasing bioactive material. Bone defects were generated in New Zealand white rabbits and the rabbits were then implanted with RPM‑loaded BHA/PAA. High‑performance liquid chromatography (HPLC) was used to determine the concentrations of rifapentine in the plasma and the local muscle tissues of the treated rabbits. Hematoxylin and eosin (H&E) staining and biochemical analyses were performed to elucidate potential side effects of RPM‑loaded BHA/PAA on the heart, liver and kidney histopathology and functions of the treated rabbits. The biocompatibility and osteogenic ability of RPM‑loaded BHA/PAA was evaluated by H&E staining. The results demonstrated that the material was completely degraded and absorbed at 12 weeks following implantation and new trabecular bone and cartilage tissues had formed. The in vivo release tests revealed that RPM‑loaded BHA/PAA exhibited sustained release profiles of rifapentine and the drug concentration in the muscle tissues remained higher than the minimum inhibitory concentration of rifapentine against Mycobacterium tuberculosis for as long as 12 weeks. In addition, RPM‑loaded BHA/PAA had no long‑term side effects to the heart, liver and kidney of the treated rabbits. In conclusion, the present study demonstrated that RPM‑loaded BHA/PAA slowly and continuously released rifapentine in vivo and exhibited no side effects on heart, liver and kidney tissues and function. Furthermore, RPM‑loaded BHA/PAA promoted new bone formation, while it was gradually degraded and absorbed. The present study provided a theoretical basis for the potential advancement in developing novel treatments for osteoarticular tuberculosis.

Topics: Alanine Transaminase; Amino Acids; Animals; Aspartate Aminotransferases; Blood Urea Nitrogen; Bone and Bones; Creatinine; Disease Models, Animal; Durapatite; Male; Microspheres; Organ Specificity; Rabbits; Rifampin

Topics: Animals; Antibiotics, Antitubercular; Biomarkers; Biopsy; Chemical and Drug Induced Liver Injury; Computational Biology; Disease Models, Animal; Gene Ontology; Lethal Dose 50; Liver; Male; Mice; Proteome; Proteomics; Rifampin

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Therapy, Combination; Ethambutol; Female; Isoniazid; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Streptomycin; Treatment Outcome; Tuberculosis, Pulmonary

During active TB in humans a spectrum of pulmonary granulomas with central necrosis and hypoxia exists. BALB/c mice, predominantly used in TB drug development, do not reproduce this complex pathology thereby inaccurately predicting clinical outcome. We found that Nos2

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Fibrosis; Foam Cells; Humans; Hypoxia; Isoniazid; Mice; Mice, Knockout; Necrosis; Nitric Oxide Synthase Type II; Rifampin; Treatment Outcome; Tuberculosis, Pulmonary

Open fractures are often complicated by infection. In cases of severe soft tissue and vascular injury, systemic antibiotics may be ineffective due to their inability to reach and provide direct antimicrobial activity to the zone of injury. High antibiotic concentrations within the wound can be achieved with reduced systemic toxicity by using local antibiotic delivery. As bacteria associated with musculoskeletal injuries frequently form biofilms, antibiotic selection is important. Herein, the use of rifampin, an antibiotic with activity against biofilms, delivered via polymethylmethacrylate (PMMA) beads is evaluated for use in a traumatic musculoskeletal wound model.. PMMA beads loaded with rifampin, or combinations of rifampin and vancomycin, were prepared and evaluated for time to curing, drug release kinetics in vitro, and infection prevention in vivo using a well-established rat model of musculoskeletal infection. A segmental bone defect was created and contaminated with methicillin susceptible Staphylococcus aureus (UAMS-1). Wounds were debrided, irrigated, and treated with PMMA beads, containing rifampin or combinations of rifampin plus vancomycin, following a 6-h (early) or 24-h (delayed) treatment. After 14days, tissue, implants, and beads were removed for bacterial quantification and assessed for rifampin resistance.. There was a direct association between loaded concentration and release kinetics of the rifampin and vancomycin from PMMA beads. Higher rifampin concentrations delayed PMMA curing times. The addition of vancomycin to PMMA resulted in more rapid release of rifampin from beads. However, the highest concentration of rifampin loaded PMMA beads (10% wt/wt) was the only treatment to significantly reduce bacterial counts. No rifampin resistance was observed.. Although higher concentrations of rifampin resulted in significant reductions of bacteria, these levels extended PMMA curing times and transformed PMMA material characteristics. While these characteristics make the material unsuitable for weight-bearing applications, such as total joint arthroplasty, the use of rifampin-loaded PMMA beads may be an effective intervention in a contaminated traumatic extremity wound due to its ability to eradicate biofilms.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Carriers; Fractures, Open; Polymethyl Methacrylate; Rats; Rats, Inbred Lew; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Vancomycin; Wound Infection

Indiscriminate use of antibiotics globally has lead to an increase in emergence of drug-resistant pathogens under both nosocomial, as well as more worryingly, in community setting as well. Further, a decrease in the corporate interest and financial commitment has exerted increasing pressure on a rapidly dwindling antimicrobial drug discovery and developmental program. In this context, we have screened the Library of Pharmacologically Active Compounds (LOPAC, Sigma) against Staphylococcus aureus and Mycobacterium tuberculosis to identify potent novel antimicrobial molecules amongst non-antibiotic molecules. Microplate-based whole cell growth assay was performed to analyze the antimicrobial potency of the compounds against Staphylococcus aureus and Mycobacterium tuberculosis. We identified diphenyleneiodonium chloride, a potent inhibitor of NADH/NADPH oxidase, as a broad-spectrum antibiotic potently active against drug resistant strains of Staphylococcus aureus and Mycobacterium tuberculosis. Intriguingly, the diphenyleneiodonium chloride was also very effective against slow-growing non-replicating Mtb persisters. FIC index demonstrated a strongly synergistic interaction between diphenyleneiodonium chloride and Rifampicin while it did not interact with INH. The antimicrobial property of the diphenyleneiodonium chloride was further validated in vivo murine neutropenic thigh S. aureus infection model. Taken together, these findings suggest that Diphenyleneiodonium chloride can be potentially repurposed for the treatment of tuberculosis and staphylococcal infections.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Repositioning; Drug Synergism; Enzyme Inhibitors; Mice; Microbial Viability; Mycobacterium tuberculosis; NADH, NADPH Oxidoreductases; Onium Compounds; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome; Tuberculosis

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Cross Infection; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Mice; Microbial Sensitivity Tests; Pneumonia, Ventilator-Associated; Polymyxin B; Proof of Concept Study; Rifampin

Using a tissue cage infection rat model, we test the anti-biofilm effect of clarithromycin on the efficacy of daptomycin and a daptomycin + rifampicin combination against methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA). In vitro: kill curves, daptomycin exposure studies and clarithromycin activity against biofilm were studied. In vivo: the efficacies of clarithromycin, daptomycin or daptomycin + clarithromycin, daptomycin + rifampicin and daptomycin + rifampicin + clarithromycin combinations were evaluated. In vitro: the addition of clarithromycin to daptomycin improved its activity only against one MRSA strain. Changes in daptomycin MIC values appeared more quickly in MSSA than in MRSA strain, and this was not modified by clarithromycin. Clarithromycin prevented biofilm formation but did not eradicate it. In vivo: the daptomycin + rifampicin combination was the most effective treatment and was not improved by the addition of clarithromycin. Daptomycin and daptomycin + clarithromycin had similar effectiveness; the combination protected against the appearance of daptomycin resistance only in one MRSA strain. Using a staphylococcal foreign-body infection model, we observed a slight effect with the addition of clarithromycin to daptomycin, which resulted in protection against the appearance of daptomycin-resistant strains. However, efficacy was not improved. Overall, our findings do not support a relevant clinical role for macrolides in treating device-related staphylococcal infections based on their anti-biofilm effect.

Topics: Animals; Anti-Bacterial Agents; Biofilms; Clarithromycin; Daptomycin; Disease Models, Animal; Drug Interactions; Drug Therapy, Combination; Foreign Bodies; Microbial Sensitivity Tests; Microbial Viability; Rats; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome

New drug regimens employing combinations of existing and experimental antimicrobial agents are needed to shorten treatment of tuberculosis (TB) in humans. The spectinamides are narrow-spectrum semisynthetic analogues of spectinomycin, modified to avoid intrinsic efflux by Mycobacterium tuberculosis . Spectinamides, including lead 1599, have been previously shown to exhibit a promising therapeutic profile in mice as single agents. Here we explore the in vivo activity of lead spectinamides when combined with other agents.. The efficacy of 1599 or 1810 was tested in combination in three increasingly advanced TB mouse models. Mice were infected by aerosol and allowed to establish acute or chronic infection, followed by treatment (≤4 weeks) with the spectinamides alone or in two- and three-drug combination regimens with existing and novel therapeutic agents. Bacteria were enumerated from lungs by plating for cfu.. Herein we show the following: (i) 1599 exhibits additive or synergistic activity with most of the first-line agents; (ii) 1599 in combination with rifampicin and pyrazinamide or with bedaquiline and pyrazinamide promotes significantly improved efficacy in the high-dose aerosol model; (iii) 1599 enhances efficacy of rifampicin or pyrazinamide in chronically infected BALB/c mice; and (iv) 1599 is synergistic when administered in combination with rifampicin and pyrazinamide in the C3HeB/FeJ mouse model showing caseous necrotic pulmonary lesions.. Spectinamides were effective partner agents for multiple anti-TB agents including bedaquiline, rifampicin and pyrazinamide. None of these in vivo synergistic interactions was predicted from in vitro MIC chequerboard assays. These data support further development of the spectinamides as combination partners with existing and experimental anti-TB agents.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Lung; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Quinolines; Rifampin; Spectinomycin; Tuberculosis

The Multistate Tuberculosis Pharmacometric (MTP) model, a pharmacokinetic-pharmacodynamic disease model, has been used to describe the effects of rifampicin on Mycobacterium tuberculosis (M. tuberculosis) in vitro. The aim of this work was to investigate if the MTP model could be used to describe the rifampicin treatment response in an acute tuberculosis mouse model. Sixty C57BL/6 mice were intratracheally infected with M. tuberculosis H37Rv strain on Day 0. Fifteen mice received no treatment and were sacrificed on Days 1, 9 and 18 (5 each day). Twenty-five mice received oral rifampicin (1, 3, 9, 26 or 98 mg·kg

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Mice; Mice, Inbred C57BL; Mycobacterium tuberculosis; Rifampin; Tuberculosis

Enterococci are a leading cause of healthcare-associated infection worldwide and display increasing levels of resistance to many of the commonly used antimicrobials, making treatment of their infections challenging. Combinations of antibiotics are occasionally employed to treat serious infections, allowing for the possibility of synergistic killing. The aim of this study was to evaluate the effects of different antibacterial combinations against enterococcal isolates using an in vitro approach and an in vivo Galleria mellonella infection model. Five Enterococcus faecalis and three Enterococcus faecium strains were screened by paired combinations of rifampicin, tigecycline, linezolid or vancomycin using the chequerboard dilution method. Antibacterial combinations that displayed synergy were selected for in vivo testing using a G. mellonella larvae infection model. Rifampicin was an effective antibacterial enhancer when used in combination with tigecycline or vancomycin, with minimum inhibitory concentrations (MICs) of each individual antibiotic being reduced by between two and four doubling dilutions, generating fractional inhibitory concentration index (FICI) values between 0.31 and 0.5. Synergy observed with the chequerboard screening assays was subsequently observed in vivo using the G. mellonella model, with combination treatment demonstrating superior protection of larvae post-infection in comparison with antibiotic monotherapy. In particular, rifampicin in combination with tigecycline or vancomycin significantly enhanced larvae survival. Addition of rifampicin to anti-enterococcal treatment regimens warrants further investigation and may prove useful in the treatment of enterococcal infections whilst prolonging the clinically useful life of currently active antibiotics.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Enterococcus faecalis; Enterococcus faecium; Gram-Positive Bacterial Infections; Lepidoptera; Microbial Sensitivity Tests; Rifampin; Survival Analysis; Treatment Outcome

Lymphatic filariasis (LF) and onchocerciasis are priority neglected tropical diseases targeted for elimination. The only safe drug treatment with substantial curative activity against the filarial nematodes responsible for LF (Brugia malayi, Wuchereria bancrofti) or onchocerciasis (Onchocerca volvulus) is doxycycline. The target of doxycycline is the essential endosymbiont, Wolbachia. Four to six weeks doxycycline therapy achieves >90% depletion of Wolbachia in worm tissues leading to blockade of embryogenesis, adult sterility and premature death 18-24 months post-treatment. Long treatment length and contraindications in children and pregnancy are obstacles to implementing doxycycline as a public health strategy. Here we determine, via preclinical infection models of Brugia malayi or Onchocerca ochengi that elevated exposures of orally-administered rifampicin can lead to Wolbachia depletions from filariae more rapidly than those achieved by doxycycline. Dose escalation of rifampicin achieves >90% Wolbachia depletion in time periods of 7 days in B. malayi and 14 days in O. ochengi. Using pharmacokinetic-pharmacodynamic modelling and mouse-human bridging analysis, we conclude that clinically relevant dose elevations of rifampicin, which have recently been determined as safe in humans, could be administered as short courses to filariasis target populations with potential to reduce anti-Wolbachia curative therapy times to between one and two weeks.

Topics: Administration, Oral; Animals; Anti-Bacterial Agents; Brugia malayi; Disease Models, Animal; DNA, Bacterial; Elephantiasis, Filarial; Embryonic Development; Filarioidea; Humans; Mice; Onchocerca volvulus; Onchocerciasis; Rifampin; Treatment Outcome; Wolbachia; Wuchereria bancrofti

Our team had previously identified certain indolecarboxamides that represented a new chemical scaffold that showed promising anti-TB activity at both an in vitro and in vivo level. Based on mutational analysis using bacteria found resistant to one of these indolecarboxamides, we identified the trehalose monomycolate transporter MmpL3 as the likely target of these compounds. In the present work, we now further elaborate on the SAR of these compounds, which has led in turn to the identification of a new analog, 4,6-difluoro-N-((1R,2R,3R,5S)-2,6,6-trimethylbicyclo[3.1.1]heptan-3-yl)-1H-indole-2-carboxamide (26), that shows excellent activity against drug-sensitive (MIC = 0.012 μM; SI ≥ 16000), multidrug-resistant (MDR), and extensively drug-resistant (XDR) Mycobacterium tuberculosis strains, has superior ADMET properties, and shows excellent activity in the TB aerosol lung infection model. Compound 26 is also shown to work in synergy with rifampin. Because of these properties, we believe that indolecarboxamide 26 is a possible candidate for advancement to human clinical trials.

Topics: Animals; Antitubercular Agents; Bacterial Proteins; Disease Models, Animal; Drug Design; Female; Humans; Indoles; Membrane Transport Proteins; Mice, Inbred BALB C; Microbial Sensitivity Tests; Models, Molecular; Molecular Docking Simulation; Molecular Targeted Therapy; Mycobacterium tuberculosis; Tuberculosis; Tuberculosis, Multidrug-Resistant

A series of biheterocyclic (1H-indole, benzofuran, pyrazolo[1,5-a]pyrimidine, pyrazolo[1,5-a]pyrimidin-5(4H)-one, imidazo[2,1-b]thiazole and pyrazolo[5,1-b]thiazole) derivatives were synthesized and evaluated for their anti-tubercular activities. The imidazo[2,1-b]thiazoles 9a-c and pyrazolo[5,1-b]thiazoles 10a-c exhibited promising anti-tubercular activity in varying degrees. Especially, the 2,6-dimethylpyrazolo[5,1-b]thiazole 10a exhibited strong suppressing function against H37Ra strain with MIC value of 0.03μg/mL. Compound 10a also displayed good pharmacokinetic profiles with oral bioavailability (F) of 41.7% and a half-life of 13.4h. Furthermore, 10a significantly reduced the bacterial burden in an autoluminescent H37Ra infected mouse model, suggesting its promising potential for development of anti-tubercular drugs.

Topics: Administration, Oral; Animals; Antitubercular Agents; Biological Availability; Chlorocebus aethiops; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Discovery; Mice; Molecular Structure; Mycobacterium tuberculosis; Rats; Structure-Activity Relationship; Tuberculosis; Vero Cells

The aim of this study was to prepare and characterize spray dried inhalable chitosan nanoparticles (CNPs) for sustained delivery of anti-tubercular drugs, isoniazid (INH) and rifampicin (RIF), to the lungs. CNPs were prepared by ionic gelation technique followed spray drying. Results showed that the CNPs obtained had a smooth spherical shape with an average size of 230 ± 4.5 nm, with a poly dispersity index of 0.180 ± 0.021. Both drugs, were detected in various organs (lungs, liver, spleen and kidney) until 24 h post nebulization. The chemotherapeutic efficacy of a single dose of drug-loaded CNPs suggested that they are more effective against the mycobacterium than free drugs.

Topics: Administration, Inhalation; Animals; Antibiotics, Antitubercular; Chitosan; Disease Models, Animal; Drug Carriers; Female; Humans; Isoniazid; Mice; Mice, Inbred BALB C; Nanoparticles; Rifampin; Tuberculosis, Pulmonary

Encapsulating antibiotics such as rifampicin in biodegradable nanoparticles provides several advantages compared to free drug administration, including reduced dosing due to localized targeting and sustained release. Consequently, these characteristics reduce systemic drug toxicity. However, new nanoformulations need to be tested in complex biological systems to fully characterize their potential for improved drug therapy. Tuberculosis, caused by infection with the bacterium Mycobacterium tuberculosis, requires lengthy and expensive treatment, and incomplete therapy contributes to an increasing incidence of drug resistance. Recent evidence suggests that standard therapy may be improved by combining antibiotics with bacterial efflux pump inhibitors, such as thioridazine. However, this drug is difficult to use clinically due to its toxicity. Here, we encapsulated thioridazine in poly(lactic-co-glycolic) acid nanoparticles and tested them alone and in combination with rifampicin nanoparticles, or free rifampicin in macrophages and in a zebrafish model of tuberculosis. Whereas free thioridazine was highly toxic in both cells and zebrafish embryos, after encapsulation in nanoparticles no toxicity was detected. When combined with rifampicin nanoparticles, the nanoparticles loaded with thioridazine gave a modest increase in killing of both Mycobacterium bovis BCG and M. tuberculosis in macrophages. In the zebrafish, the thioridazine nanoparticles showed a significant therapeutic effect in combination with rifampicin by enhancing embryo survival and reducing mycobacterial infection. Our results show that the zebrafish embryo is a highly sensitive indicator of drug toxicity and that thioridazine nanoparticle therapy can improve the antibacterial effect of rifampicin in vivo.

Topics: Animals; Antitubercular Agents; Cell Survival; Cells, Cultured; Disease Models, Animal; Drug Therapy, Combination; Female; Humans; Lactic Acid; Macrophages; Male; Mice, Inbred C57BL; Mycobacterium tuberculosis; Nanoparticles; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Rifampin; Thioridazine; Tuberculosis; Zebrafish

Previously, we investigated a locally developed technique of bonding arterial grafts with three antimicrobials to protect against early (within 2 weeks) perioperative bacterial contamination encountered occasionally during aortic graft prosthetic reconstruction. Vascular graft infections are classified by their appearance time (early [<4 months] vs late [>4 months] after graft implantation), degree of incorporation into the surrounding vessel wall, connectivity to the postoperative wound, and extent of graft involvement. In the current phase of testing, we evaluated the ability of our novel triple antimicrobial-bonded graft to prevent infection in the first 8 weeks after implantation.. At week 9, all of the grafts were explanted. All S aureus-inoculated bonded grafts (n = 5) showed no bacterial growth. The unbonded, uninoculated graft (n = 1) showed low-level bacterial growth (<1.2 × 10. Our triple-bonded aortic graft prevented perioperative aortic graft infection for at least 8 weeks in a porcine model. The synergistic antimicrobial activity of this graft was sufficient to prevent and/or eradicate infection during that period. Further studies are needed to assess the graft's ability to combat early-onset vascular graft infection for up to 4 months.

Topics: Animals; Anti-Infective Agents; Aorta, Abdominal; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Chlorhexidine; Coated Materials, Biocompatible; Disease Models, Animal; Minocycline; Polyethylene Terephthalates; Prosthesis Design; Prosthesis-Related Infections; Rifampin; Staphylococcal Infections; Swine; Swine, Miniature; Time Factors

Pyrazinamide (PZA) is a key sterilizing drug in first-line tuberculosis (TB) regimens and exerts its activity entirely during the first 2 months in human infections. We recently described the reduced activity of PZA in C3HeB/FeJ mice with large caseous tubercles due to neutral pH. Here, we aimed to determine the contribution of PZA to the sterilizing activity of the first-line TB regimen in C3HeB/FeJ and BALB/c mice. Three regimens were compared (in combinations: R, rifampin; H, isoniazid; E, ethambutol; Z, pyrazinamide; with numbers indicating the treatment duration, in months): 2RHEZ/4RH, 2RHE/4RH, and 2RHEZ/4RHZ. Lung CFU counts were assessed after 0 and 2 months of treatment, and relapse rates were assessed 3 months after 3, 4.5, and 6 months of treatment. The relapse rates after 3 months of treatment were 53% and 95% in C3HeB/FeJ mice receiving 2RHEZ/1RH and 2RHE/1RH, respectively, and 67%, 100%, and 80% in BALB/c receiving 2RHEZ/1RH, 2RHE/1RH, and 2RHEZ/1RHZ, respectively. The relapse rates after 4.5 months of treatment were 32%, 20%, and 0% in C3HeB/FeJ mice receiving 2RHEZ/2.5RH, 2RHE/2.5RH, and 2RHEZ/2.5RHZ, respectively, and 0% and 67% in BALB/c receiving 2RHEZ/2.5RH and 2RHE/2.5RH, respectively. The month-6 relapse rates were 0%, 13%, and 0% in C3HeB/FeJ mice given 2RHEZ/4RH, 2RHE/4RH, and 2RHEZ/4RHZ, respectively, and 7% in BALB/c mice receiving 2RHE/4RH. The addition of PZA shortens the duration of treatment needed to prevent relapse in both mouse strains. However, while its contribution is limited to the first 2 months of treatment in BALB/c mice, continuing PZA beyond the first 2 months is beneficial in C3HeB/FeJ mice by preventing relapse among those with the highest disease burden.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Resistance, Bacterial; Drug Therapy, Combination; Ethambutol; Female; Isoniazid; Mice, Inbred BALB C; Mice, Inbred C3H; Mutation; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Treatment Outcome; Tuberculosis, Pulmonary

Prosthetic vascular graft infection (PVGI) is an emerging disease, mostly caused by staphylococci, with limited data regarding efficacy of current antistaphylococcal agents. We aimed to assess the efficacy of different antibiotic regimens.. Six different strains of MSSA and MRSA were used. We compared results of minimal biofilm inhibitory and eradicating concentrations (MBICs and MBECs) obtained with a Calgary Biofilm Pin Lid Device (CBPD) with those yielded by an original Dacron(®)-related minimal inhibitory and eradicating concentration measure model. We then used a murine model of Staphylococcus aureus vascular prosthetic material infection to evaluate efficacy of different antibiotic regimens: vancomycin and daptomycin combined or not with rifampicin for MRSA and the same groups with cloxacillin and cloxacillin combined with rifampicin for MSSA.. We demonstrated that classical measures of MBICs and MBECs obtained with a CPBD could overestimate the decrease in antibiotic susceptibility in material-related infections and that the nature of the support used might influence the measure of biofilm susceptibility, since results yielded by our Dacron(®)-related minimal eradicating assay were lower than those found with a plastic device. In our in vivo model, we showed that daptomycin was significantly more bactericidal than comparators for some strains of MRSA or MSSA but not for all. For the majority of strains, it was as efficient as comparators. The addition of rifampicin to daptomycin did not enhance daptomycin efficacy.. Despite the heterogeneity of results according to bacterial strains, these innovative models represent an option to better evaluate the in vitro efficacy of antibiotics on Dacron(®)-related biofilm S. aureus infections, and to screen different antibiotic regimens in a mouse model of PVGIs.

Topics: Animals; Anti-Bacterial Agents; Biofilms; Daptomycin; Disease Models, Animal; Drug Therapy, Combination; Female; Mice; Microbial Sensitivity Tests; Models, Biological; Prosthesis-Related Infections; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome; Vancomycin

Experimental and clinical studies have indicated that the antileprosy drug clofazimine may contribute treatment-shortening activity when included in tuberculosis treatment regimens. Clofazimine accumulates to high levels in tissues, has a long half-life, and remains in the body for months after administration is stopped. We hypothesized that in tuberculosis treatment, accumulated clofazimine may contribute sustained antimicrobial activity after treatment cessation, and we used the BALB/c mouse model of chronic tuberculosis chemotherapy to address this hypothesis. Mycobacterium tuberculosis-infected mice were treated for 4 weeks or 8 weeks with either isoniazid alone, clofazimine alone, the first-line regimen rifampin-isoniazid-pyrazinamide-ethambutol, or a first-line regimen where clofazimine was administered in place of ethambutol. To evaluate posttreatment antimicrobial activity, bacterial regrowth in the lungs and spleens was assessed at the day of treatment cessation and 2, 4, 6, and 8 weeks after treatment was stopped. Bacterial regrowth was delayed in all mice receiving clofazimine, either alone or in combination, compared to the mice that did not receive clofazimine. This effect was especially evident in mice receiving multidrug therapy. In mice not receiving clofazimine, bacterial regrowth began almost immediately after treatment was stopped, while in mice receiving clofazimine, bacterial regrowth was delayed for up to 6 weeks, with the duration of sustained antimicrobial activity being positively associated with the time that serum clofazimine levels remained at or above the 0.25-μg/ml MIC for M. tuberculosis Thus, sustained activity of clofazimine may be important in the treatment-shortening effect associated with this drug.

Topics: Animals; Antitubercular Agents; Clofazimine; Disease Models, Animal; Drug Combinations; Drug Therapy, Combination; Ethambutol; Female; Isoniazid; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Tuberculosis; Withholding Treatment

Susceptibility to antibiotics is dramatically reduced when bacteria form biofilms. In clinical settings this has a profound impact on treatment of implant-associated infections, as these are characterized by biofilm formation. Current routine susceptibility testing of microorganisms from infected implants does not reflect the actual susceptibility, and the optimal antibiotic strategy for treating implant-associated infections is not established. In this study of biofilm formation in implant-associated osteomyelitis, we compared thein vitroandin vivoefficacy of selected antibiotics alone and in combination againstStaphylococcus aureus.We tested vancomycin, linezolid, daptomycin and tigecycline alone and in combination with rifampicin, vancomycin, linezolid and daptomycin againstS. aureusIn vitro, biofilm formation dramatically reduced susceptibility by a factor of 500-2000.In vivo, antibiotic combinations were tested in a murine model of implant-associated osteomyelitis. Mice were infected by inserting implants colonized withS. aureustrough their tibia. After 11 days, the animals were divided into different groups (five animals/group) and given 14 days of antibiotic therapy. All antibiotics resulted in a reduced bacterial load in the infected bone surrounding the implant. Overall, the most effective antibiotic combinations contained rifampicin. Combinations containing two non-rifampicin antibiotics were not more active than single drugs.

Topics: Animals; Anti-Bacterial Agents; Biofilms; Daptomycin; Disease Models, Animal; Drug Resistance, Bacterial; Drug Synergism; Drug Therapy, Combination; Female; Linezolid; Mice; Microbial Sensitivity Tests; Osteomyelitis; Prostheses and Implants; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome; Vancomycin

Nephrotoxicity is a rare complication caused by anti-tuberculosis therapy-induced oxidative stress. The Cyanobacterium Spirulina fusiformis Voronikhin belonging to Oscillatoriaceae family is used traditionally as a source of antioxidants against oxidative stress. We aimed to investigate the efficacy of S. fusiformis in modifying isoniazid (INH) and rifampicin (RIF)-induced changes in Wistar rat kidneys. Animals were divided into six groups: normal control rats; toxic control (INH & RIF-50 mg/kg b.w./d each; p.o.); INH & RIF + S. fusiformis (400 mg/kg b.w./d); INH & RIF + S. fusiformis (800 mg/kg b.w./d); S. fusiformis (800 mg/kg b.w./d) alone-treated rats; INH & RIF + silymarin (25 mg/kg b.w./d). Study duration was 28 d after which blood and kidneys were analyzed. We also studied the binding and interactions of the transcription factors Liver X Receptor (LXR) and Farnesoid X Receptor (FXR) with INH, RIF, and representative active compounds of S. fusiformis by in silico methods. INH & RIF treatment caused significant (p< 0.05) decrease in antioxidant levels and significant (p< 0.05) increase in the levels of creatinine, urea, and uric acid showing impaired kidney function. Spirulina fusiformis ameliorated these effects in a dose dependent manner. Histological examination of kidneys supported these findings. Results of the in silico analyses showed that selected active components of S. fusiformis interact with LXR and FXR and could be a possible mechanism of action. S. fusiformis rendered protection against anti-tuberculosis drugs-induced oxidative stress in kidney tissues of rats.

Topics: Acute Kidney Injury; Animals; Antioxidants; Antitubercular Agents; Creatinine; Disease Models, Animal; Female; Humans; Isoniazid; Kidney; Lipid Peroxidation; Liver; Oxidative Stress; Protective Agents; Rats; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; Rifampin; Silymarin; Spirulina; Urea; Uric Acid

Currently, the most effective tuberculosis control method involves case finding and 6 months of chemotherapy. There is a need to improve our understanding about drug interactions, combination activities, and the ability to remove persistent bacteria using the current regimens, particularly in relation to relapse. We aimed to investigate the therapeutic effects of three main components, rifampin (RMP), isoniazid (INH), and pyrazinamide (PZA), in current drug regimens using a modified version of the Cornell mouse model. We evaluated the posttreatment levels of persistent Mycobacterium tuberculosis in the organs of mice using culture filtrate derived from M. tuberculosis strain H37Rv. When RMP was combined with INH, PZA, or INH-PZA, significant additive activities were observed compared to each of the single-drug treatments. However, the combination of INH and PZA showed a less significant additive effect than either of the drugs used on their own. Apparent culture negativity of mouse organs was achieved at 14 weeks of treatment with RMP-INH, RMP-PZA, and RMP-INH-PZA, but not with INH-PZA, when conventional tests, namely, culture on solid agar and in liquid broth, indicated that the organs were negative for bacteria. The relapse rates for RMP-containing regimens were not significantly different from a 100% relapse rate at the numbers of mice examined in this study. In parallel, we examined the organs for the presence of culture filtrate-dependent persistent bacilli after 14 weeks of treatment. Culture filtrate treatment of the organs revealed persistent M. tuberculosis Modeling of mycobacterial elimination rates and evaluation of culture filtrate-dependent organisms showed promise as surrogate methods for efficient factorial evaluation of drug combinations in tuberculosis in mouse models and should be further evaluated against relapse. The presence of culture filtrate-dependent persistent M. tuberculosis is the likely cause of disease relapse in this modified Cornell mouse model.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Combinations; Female; Isoniazid; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Recurrence; Rifampin; Tuberculosis, Pulmonary

The aim of the study was to determine the effect of direct application of rifampin, povidone-iodine, and hydrogen peroxide on the formation of epidural fibrosis in rats. Forty-eight adult male Wistar albino rats were equally and randomly divided into four groups (laminectomy, topical rifampin, topical povidone-iodine, and topical hydrogen peroxide). Laminectomy was performed at the T12 level in all rats. Four weeks later, the extent of epidural fibrosis was assessed both macroscopically and histopathologically. ANOVA test was used for the evaluation of dural thickness. Kruskal-Wallis test was used for the pathology and macroscopic evaluation. Chi-square test was used for evaluation of the arachnoid involvement. p value <0.05 was accepted as statistically significant. Our data revealed that topical application of both povidone-iodine and hydrogen peroxide were effective in reducing epidural fibrosis formation. The results of our study provide the experimental evidence of the preventive effects of topical application of povidone-iodine and hydrogen peroxide over epidural fibrosis.

Topics: Administration, Topical; Animals; Disease Models, Animal; Drug Therapy, Combination; Epidural Space; Fibrosis; Hydrogen Peroxide; Male; Povidone-Iodine; Rats; Rats, Wistar; Rifampin

In recent years, whole-cell-based screens for novel small molecule inhibitors active against Mycobacterium tuberculosis in culture followed by the whole-genome sequencing of spontaneous resistant mutants have identified multiple chemical scaffolds thought to kill the bacterium through the inactivation of the mycolic acid transporter, MmpL3. Consistent with the fact that MmpL3 is required for the formation of the mycobacterial outer membrane, we have conclusively shown in this study, using conditionally regulated knockdown mutants, that mmpL3 is required for the replication and viability of M. tuberculosis, both under standard laboratory growth conditions and during the acute and chronic phases of infection in mice. Speaking for the vulnerability of this target, silencing mmpL3 had a rapid bactericidal effect on actively replicating cells in vitro and reduced by 3 to 5 logs in less than 4 weeks the bacterial loads of acutely and chronically infected mouse lungs, respectively. Depletion of MmpL3 further rendered M. tuberculosis hypersusceptible to MmpL3 inhibitors. The exquisite vulnerability of MmpL3 at all stages of the infection establishes this transporter as an attractive new target with the potential to improve and shorten current drug-susceptible and drug-resistant tuberculosis chemotherapies.

Topics: Animals; Antitubercular Agents; Bacterial Load; Bacterial Proteins; Biological Transport; Ciprofloxacin; Disease Models, Animal; Doxycycline; Female; Gene Expression; Gene Knockdown Techniques; Humans; Isoniazid; Lung; Membrane Transport Proteins; Mice; Mice, Inbred C57BL; Microbial Sensitivity Tests; Microbial Viability; Mycobacterium tuberculosis; Mycolic Acids; Rifampin; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary

The current first-line therapy for drug-susceptible tuberculosis consists of rifampicin (RIF), isoniazid (INH), pyrazinamide (PZA) and ethambutol (EMB). In this study, we determined the population pharmacokinetics (PopPK) of RIF, INH, EMB and PZA using original experimental sampling designs for single-dose intravenous (IV) and single- and multiple-dose oral administration studies in the mouse model, and used these PopPK models to develop and evaluate new, more informative sampling designs with the aim of reducing the number of animals required for each drug. The RIF, INH, EMB and PZA blood concentrations after single oral and IV doses and multiple-dose oral administrations based on the original designs were used in the PopPK analysis using NONMEM software. The final PopPK models described the data well. Stochastic simulation and estimation were used to optimise the designs. The relative bias and relative imprecision of each pharmacokinetic parameter for each drug were derived and assessed to choose the final designs. The final single-dose IV and oral designs included up to eight samples per mouse with a total of 24 mice required for RIF and EMB and 33 mice for INH and PZA. In the new multiple-dose (zipper) oral designs, the mice were divided into two groups of three per dose, and four samples were taken from each mouse to cover all seven or eight sampling time points. The final number of mice required for the multiple-dose oral designs was 30 for RIF, INH and EMB, 36 for PZA. The number of mice required in the new designs for RIF, INH and EMB was decreased by up to 7-fold and the relative bias and relative imprecision in the parameter estimates were at least similar to those in the original designs.

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Ethambutol; Isoniazid; Mice, Inbred C57BL; Models, Biological; Pyrazinamide; Rifampin; Sample Size

We compared tedizolid alone and tedizolid with rifampin to rifampin and vancomycin plus rifampin in a rat model of methicillin-resistant Staphylococcus aureus (MRSA) foreign body-associated osteomyelitis. The study strain was a prosthetic joint infection-associated isolate. Steady-state pharmacokinetics for intraperitoneal administration of tedizolid, vancomycin, and rifampin were determined in uninfected rats. MRSA was inoculated into the proximal tibia, and a wire was implanted. Four weeks later, the rats were treated intraperitoneally for 21 days with tedizolid (n = 14), tedizolid plus rifampin (n = 11), rifampin (n = 16), or vancomycin plus rifampin (n = 13). Seventeen rats received no treatment. After treatment, quantitative bone cultures were performed. Blood was obtained for determination of drug trough concentrations in the tedizolid and tedizolid plus rifampin groups. The mean peak plasma concentration and mean area under the concentration-time curve from time zero to 24 h for tedizolid were 12 μg/ml and 60 μg · h/ml, respectively. The bacterial loads in all treatment groups were significantly lower than those in the control group; those in the tedizolid- plus rifampin-treated animals were not significantly different from those in the vancomycin- plus rifampin-treated animals. The range of mean plasma trough concentrations in the tedizolid group was 0.44 to 0.73 μg/ml. Although neither tedizolid nor vancomycin resistance was detected in isolates recovered from bones, rifampin resistance was detected in 10 animals (63%) in the rifampin group, 8 animals (73%) in the tedizolid plus rifampin group, and a single animal (8%) in the vancomycin plus rifampin group. Tedizolid alone or tedizolid combined with rifampin was active in a rat model of MRSA foreign body-associated osteomyelitis. The emergence of rifampin resistance was noted in animals receiving tedizolid plus rifampin.

Topics: Animals; Anti-Bacterial Agents; Bacterial Load; Bone Wires; Disease Models, Animal; Drug Combinations; Drug Resistance, Bacterial; Foreign Bodies; Injections, Intraperitoneal; Male; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Organophosphates; Osteomyelitis; Oxazoles; Rats; Rats, Wistar; Rifampin; Staphylococcal Infections; Tibia; Vancomycin

Aggregation of alpha synuclein (α-syn) leading to dopaminergic neuronal death has been recognized as one of the main pathogenic factors in the initiation and progression of Parkinson's disease (PD). Consequently, α-syn has been targeted for the development of therapeutics for PD. We have developed a novel assay to screen compounds with α-syn modulating properties by mimicking recent findings from in vivo animal studies involving intrastriatal administration of pre-formed fibrils in mice, resulting in increased α-syn pathology accompanying the formation of Lewy-body (LB) type inclusions. We found that in vitro generated α-syn pre-formed fibrils induce seeding of α-syn monomers to produce aggregates in a dose-and time-dependent manner under static conditions in vitro. These aggregates were toxic towards rat pheochromocytoma cells (PC12). Our novel multifunctional dopamine agonists D-519 and D-520 exhibited significant neuroprotection in this assay, while their parent molecules did not. The neuroprotective properties of our compounds were further evaluated in a Drosophila model of synucleinopathy. Both of our compounds showed protective properties in fly eyes against the toxicity caused by α-syn. Thus, our in vitro results on modulation of aggregation and toxicity of α-syn by our novel assay were further validated with the in vivo experiments.

Topics: alpha-Synuclein; Animals; Benzothiazoles; Biological Assay; Circular Dichroism; Disease Models, Animal; Dopamine Agonists; Drosophila melanogaster; Eye; PC12 Cells; Pramipexole; Protein Aggregates; Protein Structure, Secondary; Rats; Rifampin; Tetrahydronaphthalenes

Antimicrobial treatment of chlamydial infections is known to be of limited efficacy. In this study, effects of doxycycline (D), usually the drug of choice, were compared with the combined therapy of doxycycline and rifampicin (R) in a bovine model of respiratory Chlamydia psittaci infection. After intrabronchial inoculation of the pathogen, 30 animals were assigned to five groups (n = 6 per group): untreated controls, monotherapy with D (5 mg kg(-1)day(-1) or 10 mg kg(-1)day(-1)), and combination therapy of D and R (600 mg day(-1)). Treatment continued until day 14 post inoculation (d.p.i.). Clinical signs, inflammatory markers, and pathological findings confirmed successful infection in all animals. Reisolation of the pathogen was possible in 4/6 untreated animals and in 4/12 animals treated with D alone until 4 d.p.i., but in none of the calves of the two D + R groups. Pathogen detection was possible in all animals without significant differences among groups. Severity of disease and time course of its resolution, assessed by clinical and pathological findings as well as inflammatory parameters, were not significantly different between untreated controls and calves receiving D alone or in combination with R. Regardless of the treatment regimen, all groups recovered clinically and cleared the infection within 2 weeks.

Topics: Animals; Anti-Bacterial Agents; Bronchoalveolar Lavage Fluid; Cattle; Chlamydophila psittaci; Disease Models, Animal; Doxycycline; Drug Therapy, Combination; Lung; Male; Prospective Studies; Psittacosis; Rifampin; Severity of Illness Index; Time Factors; Treatment Outcome

While active tuberculosis (TB) is a treatable disease, many complex factors prevent its global elimination. Part of the difficulty in developing optimal therapies is the large design space of antibiotic doses, regimens and combinations. Computational models that capture the spatial and temporal dynamics of antibiotics at the site of infection can aid in reducing the design space of costly and time-consuming animal pre-clinical and human clinical trials. The site of infection in TB is the granuloma, a collection of immune cells and bacteria that form in the lung, and new data suggest that penetration of drugs throughout granulomas is problematic. Here we integrate our computational model of granuloma formation and function with models for plasma pharmacokinetics, lung tissue pharmacokinetics and pharmacodynamics for two first line anti-TB antibiotics. The integrated model is calibrated to animal data. We make four predictions. First, antibiotics are frequently below effective concentrations inside granulomas, leading to bacterial growth between doses and contributing to the long treatment periods required for TB. Second, antibiotic concentration gradients form within granulomas, with lower concentrations toward their centers. Third, during antibiotic treatment, bacterial subpopulations are similar for INH and RIF treatment: mostly intracellular with extracellular bacteria located in areas non-permissive for replication (hypoxic areas), presenting a slowly increasing target population over time. Finally, we find that on an individual granuloma basis, pre-treatment infection severity (including bacterial burden, host cell activation and host cell death) is predictive of treatment outcome.

Topics: Animals; Anti-Bacterial Agents; Antitubercular Agents; Calibration; Computer Simulation; Disease Models, Animal; Dose-Response Relationship, Drug; Granuloma; Humans; Immunity; Isoniazid; Mice; Models, Biological; Mycobacterium tuberculosis; Primates; Rifampin; Time Factors; Treatment Outcome; Tuberculosis

The present study has been designed to investigate the potential of rifampicin [Pregnane X receptors (PXR) agonist] in experimental dementia. Aluminum chloride (AlCl3) [100mg/kg, p.o. for 42days] was administered to Wistar rats (n=6) to induce dementia. Morris water maze (MWM) test was used to assess learning and memory and rota rod test was used to assess locomotor activity of the animals. A battery of biochemical tests and histopathological evaluation using hematoxylin and eosin (H&E) and Congo Red stains were performed at the end of the study. AlCl3-treated rats demonstrated impaired cognition and locomotor activity on MWM apparatus and rota rod test, respectively. These animals exhibited a significant rise in acetylcholinesterase (AChE) activity (138±3.6), thiobarbituric acid reactive species (TBARS) level (15±1.6), nitrite (56±2.4) level and myeloperoxidase (MPO) activity (4.1±0.9) along with decline in reduced glutathione (GSH) level (22±1.3) in comparison to the control group (p<0.05). Further the H&E and Congo Red-stained cerebral cortex sections of AlCl3-treated rats indicated severe neutrophilic infiltration and amyloid deposition. Rifampicin-treated AlCl3-rats exhibited significant attenuation in memory deficits, biochemical parameters like AChE activity (33±1.4), TBARS level (4.1±1.0), nitrite level (64±2.6), MPO activity (3.6±1.0) and GSH level (53±2.4) along with improved histopathological alterations and locomotor activity when compared with AlCl3-treated rats (p<0.05). Combined administration of ketoconazole (a PXR antagonist) and rifampicin to AlCl3-treated animals reversed the rifampicin-induced protective effects. Therefore the results obtained from the study indicate a defensive role of rifampicin in memory dysfunction which may probably be due to its anti-cholinesterase, anti-oxidative, anti-inflammatory and amyloid lowering effects. Moreover the study speculates the potential of PXR in the pathophysiology of dementia which is subject to further evaluation.

Topics: Acetylcholinesterase; Aluminum Chloride; Aluminum Compounds; Amyloid; Animals; Brain; Chlorides; Cognition; Dementia; Disease Models, Animal; Female; Glutathione; Ketoconazole; Male; Motor Activity; Neutrophils; Nitrites; Nootropic Agents; Peroxidase; Pregnane X Receptor; Rats, Wistar; Receptors, Steroid; Rifampin; Thiobarbituric Acid Reactive Substances

Implant-associated methicillin-resistant Staphylococcus aureus (MRSA) infections are challenging to treat. We compared antimicrobial activities in a rat model of chronic osteomyelitis in the context of retention of the foreign body without débridement.. MRSA was inoculated into the proximal tibia and a wire implanted. Four weeks after infection, treatment with vancomycin 50 mg/kg every 12 h, tigecycline 14 mg/kg every 12 h, rifampin 25 mg/kg every 12 h, or the combination of vancomycin or tigecycline plus rifampin was administered intraperitoneally for 21 days.. MRSA was cultured from all tibias in the control group (median, 6.06 log10 CFU/g bone). Median bacterial counts (log10 CFU/g) at 48 h post-treatment were 6.16 for vancomycin (p = 0.753), 2.29 for vancomycin plus rifampin (p < 0.001), 5.90 for tigecycline (p = 0.270), 0.10 for tigecycline plus rifampin (p < 0.001), and 0.91 for rifampin (p = 0.044) treatment. Three deaths were observed in the tigecycline plus rifampin group. Median bacterial counts (log10 CFU/g) at two weeks post-treatment were 5.65 for vancomycin (p = 0.6), 4.05 for vancomycin plus rifampin (p = 0.105), 5.68 for tigecycline (p = 0.401), 4.05 for tigecycline plus rifampin (p = 0.028), and 5.98 for rifampin (p = 0.297) treatment.. Tigecycline plus rifampin resulted in a significant bacterial count decrease, an effect more prominent at 48 h than two weeks after treatment completion. Tigecycline was not well tolerated at the dose studied.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Humans; Male; Methicillin; Methicillin Resistance; Methicillin-Resistant Staphylococcus aureus; Minocycline; Osteomyelitis; Rats; Rats, Wistar; Rifampin; Staphylococcal Infections; Tigecycline; Vancomycin

Rhodococcus equi, a facultative intracellular pathogen and an important cause of pneumonia in foals, is highly susceptible to killing by gentamicin in vitro. However, gentamicin is not effective in vivo, due to its poor cellular penetration. Encapsulation of drugs in liposomes enhances cellular uptake. The objectives of this study were to compare liposomal gentamicin and free gentamicin with respect to their uptake by equine macrophages and intracellular colocalization with R. equi and to compare the efficacies of liposomal gentamicin, free gentamicin and clarithromycin with rifampin for the reduction of R. equi CFU in a mouse model of infection. After ex vivo exposure, a significantly higher mean (±SD) percentage of equine alveolar macrophages contained liposomal gentamicin (91.9±7.6%) as opposed to free gentamicin (16.8±12.5%). Intracellular colocalization of drug and R. equi, as assessed by confocal microscopy, occurred in a significantly higher proportion of cells exposed to liposomal gentamicin (81.2±17.8%) compared to those exposed to free gentamicin (10.4±8.7%). The number of R. equi CFU in the spleen was significantly lower in mice treated with liposomal gentamicin compared to that of mice treated with free gentamicin or to untreated control mice. Treatment with liposomal gentamicin also resulted in a significantly greater reduction in the number of R. equi CFU in the liver compared to treatment with clarithromycin in combination with rifampin. These results support further investigation of liposomal gentamicin as a new treatment for infections caused by R. equi.

Topics: Actinomycetales Infections; Animals; Anti-Bacterial Agents; Clarithromycin; Disease Models, Animal; Gentamicins; Horse Diseases; Horses; Liposomes; Liver; Macrophages, Alveolar; Male; Mice; Mice, Nude; Pneumonia; Rhodococcus equi; Rifampin; Spleen

Although TB immunotherapy improves the results of conventional drug treatment, the effects of combining chemotherapy and immunotherapy have never been systematically evaluated. We used a comprehensive lung transcriptome analysis to directly compare the activity of combined chemotherapy and immunotherapy with that of single treatments in a mouse model of TB.. Mycobacterium tuberculosis-infected mice in the chronic phase of the disease (day 30) received: (i) isoniazid and rifampicin (drugs) daily for 30 days; (ii) DNA immunotherapy (DNA), consisting of four 100 μg injections at 10 day intervals; (iii) both therapies (DNA + drugs); or (iv) saline. The effects were evaluated 10 days after the end of treatment (day 70 post-infection).. In all groups a systemic reduction in the load of bacilli was observed, bacilli became undetectable in the drugs and DNA + drugs groups, but the whole lung transcriptome analysis showed 867 genes exclusively modulated by the DNA + drugs combination. Gene enrichment analysis indicated that DNA + drugs treatment provided synergistic effects, including the down-regulation of proinflammatory cytokines and mediators of fibrosis, as confirmed by real-time PCR, ELISA, histopathology and hydroxyproline assay.. Our results provide a molecular basis for the advantages of TB treatment using combined chemotherapy and DNA immunotherapy and demonstrate the synergistic effects obtained with this strategy.

Topics: Animals; Antitubercular Agents; Combined Modality Therapy; Disease Models, Animal; Drug Therapy; Gene Expression Profiling; Immunotherapy; Isoniazid; Lung; Mice, Inbred BALB C; Mycobacterium tuberculosis; Rifampin; Treatment Outcome; Tuberculosis; Vaccines, DNA

Chlamydia psittaci is a zoonotic bacterium with a wide host range that can cause respiratory disease in humans and cattle. In the present study, effects of treatment with macrolides and quinolones applied alone or in combination with rifampicin were tested in a previously established bovine model of respiratory C. psittaci infection. Fifty animals were inoculated intrabronchially at the age of 6-8 weeks. Seven served as untreated controls, the others were assigned to seven treatment groups: (i) rifampicin, (ii) enrofloxacin, (iii) enrofloxacin + rifampicin, (iv) azithromycin, (v) azithromycin + rifampicin, (vi) erythromycin, and (vii) erythromycin + rifampicin. Treatment started 30 hours after inoculation and continued until 14 days after inoculation (dpi), when all animals were necropsied. The infection was successful in all animals and sufficient antibiotic levels were detected in blood plasma and tissue of the treated animals. Reisolation of the pathogen was achieved more often from untreated animals than from other groups. Nevertheless, pathogen detection by PCR was possible to the same extent in all animals and there were no significant differences between treated and untreated animals in terms of local (i.e., cell count and differentiation of BALF-cells) and systemic inflammation (i.e. white blood cells and concentration of acute phase protein LBP), clinical signs, and pathological findings at necropsy. Regardless of the reduced reisolation rate in treated animals, the treatment of experimentally induced respiratory C. psittaci infection with enrofloxacin, azithromycin or erythromycin alone or in combination with rifampicin was without obvious benefit for the host, since no significant differences in clinical and pathological findings or inflammatory parameters were detected and all animals recovered clinically within two weeks.

Topics: Animals; Anti-Bacterial Agents; Azithromycin; Cattle; Chlamydophila psittaci; Disease Models, Animal; Enrofloxacin; Erythromycin; Fluoroquinolones; Inflammation; Macrolides; Male; Psittacosis; Rifampin

Due to the emergence of multidrug-resistant and extensively drug-resistant tuberculosis (TB), there is an urgent need for new TB drugs or for compounds that improve the efficacy of currently used drugs. In this study, time-kill kinetics of SILA-421 as a single drug and in combination with isoniazid (INH), rifampicin (RIF), moxifloxacin (MXF) or amikacin (AMK) against Mycobacterium tuberculosis were assessed. Therapeutic efficacy in vivo in a mouse TB model was also studied. Further in vitro analysis was performed with a RIF-susceptible and RIF-resistant strains of M. tuberculosis. When used as a single drug, SILA-421 in vitro showed concentration-dependent and time-dependent bactericidal activity. SILA-421 also enhanced the activity of INH and RIF, resulting in synergy in the case of INH. Emergence of INH resistance following exposure to INH can be prevented by the addition SILA-421. SILA-421 had no additional value in combination with MXF or AMK. Furthermore, SILA-421 enhanced the activity of RIF towards a RIF-resistant strain and resulted in complete elimination of RIF-resistant mycobacteria. Unfortunately, in mice with TB induced by a Beijing genotype strain, addition of SILA-421 to an isoniazid-rifampicin-pyrazinamide regimen for 13 weeks did not result in enhanced therapeutic efficacy.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Resistance, Bacterial; Drug Synergism; Drug Therapy, Combination; Female; Mice, Inbred BALB C; Microbial Viability; Mycobacterium tuberculosis; Piperazines; Rifampin; Siloxanes; Treatment Outcome; Tuberculosis

Orthopedic foreign body-associated infections are often treated with rifampin-based combination antimicrobial therapy. We previously observed that rifampin-resistant and methicillin-resistant Staphylococcus aureus (MRSA) isolates were present 2 days after cessation of rifampin therapy in experimental foreign body osteomyelitis. Unexpectedly, only rifampin-susceptible isolates were detected 14 days after the completion of treatment. We studied two rifampin-resistant isolates recovered 2 days after treatment and one rifampin-susceptible isolate recovered 14 days after treatment. Growing these isolates alone in vitro or in vivo demonstrated no fitness defects; however, in mixed culture, rifampin-susceptible bacteria outcompeted rifampin-resistant bacteria. In vivo, two courses of rifampin treatment (25 mg/kg of body weight every 12 h for 21 days) yielded a greater decrease in bacterial quantity in the bones of treated animals 14 days following treatment than that in animals receiving a single course of treatment (P = 0.0398). In infections established with equal numbers of rifampin-resistant and rifampin-susceptible bacteria, one course of rifampin treatment did not affect bacterial quantities. Rifampin-resistant and rifampin-susceptible isolates were recovered both 2 days and 14 days following treatment completion; however, the proportion of animals with rifampin-resistant isolates was lower at 14 days than that at 2 days following treatment completion (P = 0.024). In untreated animals infected with equal numbers of rifampin-resistant and rifampin-susceptible bacteria for 4 weeks, rifampin-susceptible isolates were exclusively recovered, indicating the outcompetition of rifampin-resistant by rifampin-susceptible isolates. The data presented imply that although there is no apparent fitness defect in rifampin-resistant bacteria when grown alone, they are outcompeted by rifampin-susceptible bacteria when the two are present together. The findings also suggest that selected rifampin resistance may not persist in initially rifampin-susceptible infections following the discontinuation of rifampin.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Foreign Bodies; Male; Methicillin; Methicillin Resistance; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Osteomyelitis; Rats; Rats, Wistar; Rifampin; Staphylococcal Infections

One critical approach to preclinical evaluation of anti-tuberculosis (anti-TB) drugs is the study of correlations between drug exposure and efficacy in animal TB infection models. While such pharmacokinetic/pharmacodynamic (PK/PD) studies are useful for the identification of optimal clinical dosing regimens, they are resource intensive and are not routinely performed. A mathematical model capable of simulating the PK/PD properties of drug therapy for experimental TB offers a way to mitigate some of the practical obstacles to determining the PK/PD index that best correlates with efficacy. Here, we present a preliminary physiologically based PK/PD model of rifampin therapy in a mouse TB infection model. The computational framework integrates whole-body rifampin PKs, cell population dynamics for the host immune response to Mycobacterium tuberculosis infection, drug-bacteria interactions, and a Bayesian method for parameter estimation. As an initial application, we calibrated the model to a set of available rifampin PK/PD data and simulated a separate dose fractionation experiment for bacterial killing kinetics in the lungs of TB-infected mice. The simulation results qualitatively agreed with the experimentally observed PK/PD correlations, including the identification of area under the concentration-time curve as best correlating with efficacy. This single-drug framework is aimed toward extension to multiple anti-TB drugs in order to facilitate development of optimal combination regimens.

Topics: Animals; Antibiotics, Antitubercular; Bayes Theorem; Computer Simulation; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Mice; Models, Biological; Monte Carlo Method; Mycobacterium tuberculosis; Rifampin; Tuberculosis, Pulmonary

Whilst levofloxacin (LVX) in combination with rifampicin (RIF) is considered the optimal treatment for prosthetic joint infection (PJI) caused by meticillin-susceptible Staphylococcus aureus (MSSA), no therapeutic alternatives have been accurately evaluated. Based on the high effectiveness of the combination of daptomycin (DAP) plus RIF against meticillin-resistant S. aureus (MRSA) in this setting, in this study the efficacy of DAP+RIF and DAP+LVX combinations was tested as alternative therapies for foreign-body infections (FBIs) caused by MSSA. A tissue-cage infection model was performed using an MSSA strain. Male Wistar rats were treated for 7 days with LVX, DAP, RIF or the combinations LVX+RIF, DAP+RIF and DAP+LVX. Antibiotic efficacy was evaluated by bacterial counts from tissue cage fluid (TCF) and the cure rate was determined from adhered bacteria. Resistance was screened. Monotherapies were less effective than combinations (P<0.05), and resistance to DAP and RIF emerged. DAP+RIF (decrease in bacterial counts in TCF, -4.9logCFU/mL; cure rate, 92%) was the most effective therapy (P<0.05). There were no differences between LVX+RIF (-3.4logCFU/mL; 11%) and DAP+LVX (-3.3logCFU/mL; 47%). No resistant strains appeared with combined therapies. In conclusion, the combinations DAP+RIF and DAP+LVX showed good efficacy and prevented resistance. DAP+RIF provided higher efficacy than LVX+RIF. These DAP combinations were efficacious alternatives therapies for MSSA FBI. Further studies should confirm whether DAP+RIF may be useful as a first-line therapy in the setting of PJI caused by MSSA.

Topics: Animals; Anti-Bacterial Agents; Colony Count, Microbial; Complementary Therapies; Daptomycin; Disease Models, Animal; Drug Therapy, Combination; Foreign Bodies; Levofloxacin; Male; Rats, Wistar; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome

Respiratory anthrax is a fatal disease in the absence of early treatment with antibiotics. Rabbits are highly susceptible to infection with Bacillus anthracis spores by intranasal instillation, succumbing within 2 to 4 days postinfection. This study aims to test the efficiency of antibiotic therapy to treat systemic anthrax in this relevant animal model. Delaying the initiation of antibiotic administration to more than 24 h postinfection resulted in animals with systemic anthrax in various degrees of bacteremia and toxemia. As the onset of symptoms in humans was reported to start on days 1 to 7 postexposure, delaying the initiation of treatment by 24 to 48 h (time frame for mass distribution of antibiotics) may result in sick populations. We evaluated the efficacy of antibiotic administration as a function of bacteremia levels at the time of treatment initiation. Here we compare the efficacy of treatment with clarithromycin, amoxicillin-clavulanic acid (Augmentin), imipenem, vancomycin, rifampin, and linezolid to the previously reported efficacy of doxycycline and ciprofloxacin. We demonstrate that treatment with amoxicillin-clavulanic acid, imipenem, vancomycin, and linezolid were as effective as doxycycline and ciprofloxacin, curing rabbits exhibiting bacteremia levels of up to 10(5) CFU/ml. Clarithromycin and rifampin were shown to be effective only as a postexposure prophylactic treatment but failed to treat the systemic (bacteremic) phase of anthrax. Furthermore, we evaluate the contribution of combined treatment of clindamycin and ciprofloxacin, which demonstrated improvement in efficacy compared to ciprofloxacin alone.

Topics: Amoxicillin-Potassium Clavulanate Combination; Animals; Anthrax; Anti-Bacterial Agents; Bacillus anthracis; Bacteremia; Ciprofloxacin; Clarithromycin; Disease Models, Animal; Doxycycline; Drug Combinations; Drug Synergism; Humans; Imipenem; Linezolid; Male; Microbial Sensitivity Tests; Rabbits; Respiratory Tract Infections; Rifampin; Spores, Bacterial; Survival Analysis; Vancomycin

Mutant huntingtin (mHtt) aggregation in the nucleus is the most readily apparent phenotype and cause of neuronal death in Huntington's disease (HD). Inhibiting mHtt aggregation reduces cell death in the brain and is thus a promising therapeutic approach. The results of the present study demonstrated that mHtt aggregation in the nucleus was altered by the activity of multidrug resistance protein 1 (MDR1), which was experimentally modulated by verapamil, siRNA and an expression vector. MDR1 detoxifies drugs and metabolites through its excretory functions in the membrane compartment, thereby protecting cells against death or senescence. When they were treated with verapamil, R6/2 mice showed a progressive decline in rotarod performance and increased mHtt aggregation in the brain. Using neuronal stem cells from R6/2 mice, we developed an in vitro HD model to test mHtt accumulation in the nuclei of neurons. When MDR1 activity in cells was decreased by verapamil or siRNA, mHtt aggregation in the nuclei increased, whereas the induction of MDR1 resulted in a decrease in mHtt aggregation. Thus, our data provide evidence that MDR1 plays an important role in the clearance of mHtt aggregation and may thus be a potential target for improving the survival of neurons in Huntington's disease.

Topics: Animals; ATP Binding Cassette Transporter, Subfamily B, Member 1; Blotting, Western; Cells, Cultured; Disease Models, Animal; Female; Humans; Huntingtin Protein; Huntington Disease; Immunohistochemistry; Male; Mice, Transgenic; Motor Activity; Mutation; Nerve Tissue Proteins; Neurons; Nucleic Acid Synthesis Inhibitors; Protein Aggregation, Pathological; Reverse Transcriptase Polymerase Chain Reaction; Rifampin; RNA Interference; Vasodilator Agents; Verapamil

Socially anxious cannabis users are influenced by cannabis expectancies and normative perceptions. The present study examines the influence of psychosocial factors on cannabis use vulnerability factors as the result of interactions between norms perceptions, social anxiety, and expectancies.. Participants were 149 (36.2% female) current cannabis users aged 18-36 (. Among cannabis users with perceptions of greater injunctive norms, social anxiety was associated with greater cannabis craving when tension reduction expectancies were greater. However, social anxiety was unrelated to cannabis craving when expectances were low. This suggests that cannabis craving among socially anxious adults was greatest when cannabis use was viewed as acceptable and expected to reduce tension, and highlights the importance of considering norms, expectancies, and social anxiety in understanding cannabis-related behaviors.. The A876P-substitution bridges in vitro and in vivo studies using J6/JFH1-based recombinants. We provide the first in vivo evidence that HVR1 protects cross-genotype conserved HCV neutralisation epitopes, which advocates the possibility of using HVR1-deleted viruses as vaccine antigens to boost broadly reactive protective nAb responses.. We conclude that the photo-processing of eVSGs leads to the production of PAHs with attached aliphatic sidegroups that are revealed by the 3.4. De 4,331 publicaciones encontradas, 16 estudios cumplieron con los criterios de inclusión. El 50 % (8/16) de los estudios revisados fueron realizados en países de Sur América, Centro América y del Caribe. El diseño de casos y controles fue el más frecuente. El anterior sistema de clasificación de casos (OMS-1997) fue utilizado en todos los estudios incluidos en esta revisión.. El estrés oxidativo-nitrosativo se encuentra presente en el curso de la infección por virus dengue, demostrado por los cambios en las concentraciones plasmáticas de óxido nítrico, antioxidantes y marcadores de lipoperoxidación y de oxidación de proteínas. Por último, parece existir una asociación entre la elevación de los niveles plasmáticos de los carbonilos proteicos y malondialdehído con la severidad del dengue.

Topics: Acid-Base Imbalance; Acidosis, Renal Tubular; Aged; Air Pollution, Indoor; Amino Acid Substitution; Animals; Animals, Newborn; Anti-Bacterial Agents; Antibodies, Neutralizing; Apoptosis; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Bone Marrow Transplantation; Carbonic Anhydrase Inhibitors; Castleman Disease; Cat Diseases; Cats; Cell Proliferation; Cell- and Tissue-Based Therapy; Chemical and Drug Induced Liver Injury; Chemotaxis, Leukocyte; Clinical Trials as Topic; Coated Materials, Biocompatible; Diagnosis, Differential; Disease Models, Animal; Environmental Monitoring; Female; Gas Chromatography-Mass Spectrometry; Genotype; Granuloma, Foreign-Body; Heart Failure; Hepacivirus; Hepatitis C; Horse Diseases; Horses; Housing; Humans; Hypercalcemia; Hypokalemia; Immunophenotyping; In Vitro Techniques; Liver; Liver Function Tests; Lymphocytes; Macrophages; Male; Medicine, Chinese Traditional; Metabolomics; Mice; Mice, Inbred C57BL; Middle Aged; Models, Animal; Mutation; Myocardial Ischemia; Neovascularization, Physiologic; Neutrophil Infiltration; Ocular Hypertension; Ophthalmic Solutions; Parathyroid Hormone; Particulate Matter; Polyethylene Terephthalates; Prednisolone; Prospective Studies; Prosthesis Design; Prosthesis-Related Infections; Rats; Rats, Wistar; Reactive Oxygen Species; Rifampin; Saponins; Sepsis; Skin; Stem Cells; Stroke Volume; Sulfonamides; Texas; Thiophenes; Time Factors; Ventricular Dysfunction, Left; Ventricular Function, Left; Viral Hepatitis Vaccines; Viral Nonstructural Proteins; Viral Proteins; Vitamin D; Wound Healing

Enterococcal implant-associated infections are difficult to treat because antibiotics generally lack activity against enterococcal biofilms. We investigated fosfomycin, rifampin, and their combinations against planktonic and adherent Enterococcus faecalis (ATCC 19433) in vitro and in a foreign-body infection model. The MIC/MBClog values were 32/>512 μg/ml for fosfomycin, 4/>64 μg/ml for rifampin, 1/2 μg/ml for ampicillin, 2/>256 μg/ml for linezolid, 16/32 μg/ml for gentamicin, 1/>64 μg/ml for vancomycin, and 1/5 μg/ml for daptomycin. In time-kill studies, fosfomycin was bactericidal at 8× and 16× MIC, but regrowth of resistant strains occurred after 24 h. With the exception of gentamicin, no complete inhibition of growth-related heat production was observed with other antimicrobials on early (3 h) or mature (24 h) biofilms. In the animal model, fosfomycin alone or in combination with daptomycin reduced planktonic counts by ≈4 log10 CFU/ml below the levels before treatment. Fosfomycin cleared planktonic bacteria from 74% of cage fluids (i.e., no growth in aspirated fluid) and eradicated biofilm bacteria from 43% of cages (i.e., no growth from removed cages). In combination with gentamicin, fosfomycin cleared 77% and cured 58% of cages; in combination with vancomycin, fosfomycin cleared 33% and cured 18% of cages; in combination with daptomycin, fosfomycin cleared 75% and cured 17% of cages. Rifampin showed no activity on planktonic or adherent E. faecalis, whereas in combination with daptomycin it cured 17% and with fosfomycin it cured 25% of cages. Emergence of fosfomycin resistance was not observed in vivo. In conclusion, fosfomycin showed activity against planktonic and adherent E. faecalis. Its role against enterococcal biofilms should be further investigated, especially in combination with rifampin and/or daptomycin treatment.

Topics: Acetamides; Ampicillin; Animals; Anti-Bacterial Agents; Bacterial Adhesion; Biofilms; Calorimetry; Daptomycin; Disease Models, Animal; Drug Therapy, Combination; Enterococcus faecalis; Foreign Bodies; Fosfomycin; Gentamicins; Gram-Positive Bacterial Infections; Guinea Pigs; Linezolid; Male; Microbial Sensitivity Tests; Oxazolidinones; Rifampin; Vancomycin

Tarvada [Cassia auriculata Linn. (Caesalpiniaceae)] is used against liver ailments in Indian folk medicine, but there is a lack of scientific evidence for this traditional claim.. The present study investigated the protective effect of methanol extract of tarvada (MECA) roots on ethanol and antitubercular drug induced hepatotoxicity in rats.. In the therapeutic model, ethanol (40%, 4 g/kg b.w., p.o.) was administered to rats for 21 days and the intoxicated rats were treated with MECA (300 and 600 mg/kg, b.w.) and silymarin (100 mg/kg, b.w.) for next 7 days. In the prophylactic model, MECA and silymarin were administered simultaneously along with a combination of isoniazid (27 mg/kg, b.w.), rifampicin (54 mg/kg, b.w.) and pyrazinamide (135 mg/kg, b.w.) for 30 days. After the study duration, serum levels of AST, ALT, ALP, total bilirubin, total cholesterol, total protein, albumin were estimated along with hepatic catalase (CAT), reduced glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA) and liver histopathology in each group.. Administration of tarvada root extract significantly (p < 0.01 and p < 0.05) lowered the elevated levels of serum AST, ALT, ALP, total bilirubin, total cholesterol, total protein and restored the abnormal levels of enzymatic antioxidants and MDA in liver due to toxicant administration in a dose-dependent manner. These results were confirmed by histopathological analysis.. Results suggest that tarvada root extract possess potent hepatoprotective activity against ethanol and antitubercular drug-induced hepatotoxicity in rats, which could be due to an inhibition of hepatic metabolizing enzymes and antioxidant activity.

Topics: Animals; Antioxidants; Antitubercular Agents; Cassia; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Dose-Response Relationship, Drug; Ethanol; Female; India; Isoniazid; Male; Medicine, Traditional; Plant Extracts; Plant Roots; Pyrazinamide; Rats; Rats, Wistar; Rifampin; Silymarin

The intestinal epithelial barrier plays a key role in the maintenance of homeostasis within the gastrointestinal tract. Barrier dysfunction leading to increased epithelial permeability is associated with a number of gastrointestinal disorders including the inflammatory bowel diseases (IBD) - Crohn's disease and ulcerative colitis. It is thought that the increased permeability in patients with IBD may be driven by alterations in the epithelial wound healing response. To this end considerable study has been undertaken to identify signaling pathways that may accelerate intestinal epithelial wound healing and normalize the barrier dysfunction observed in IBD. In the current study we examined the role of the pregnane X receptor (PXR) in modulating the intestinal epithelial wound healing response. Mutations and reduced mucosal expression of the PXR are associated with IBD, and others have reported that PXR agonists can dampen intestinal inflammation. Furthermore, stimulation of the PXR has been associated with increased cell migration and proliferation, two of the key processes involved in wound healing. We hypothesized that PXR agonists would enhance intestinal epithelial repair. Stimulation of Caco-2 intestinal epithelial cells with rifaximin, rifampicin and SR12813, all potent agonists of the PXR, significantly increased wound closure. This effect was driven by p38 MAP kinase-dependent cell migration, and occurred in the absence of cell proliferation. Treating mice with a rodent specific PXR agonist, pregnenolone 16α-carbonitrile (PCN), attenuated the intestinal barrier dysfunction observed in the dextran sulphate sodium (DSS) model of experimental colitis, an effect that occurred independent of the known anti-inflammatory effects of PCN. Taken together our data indicate that the activation of the PXR can enhance intestinal epithelial repair and suggest that targeting the PXR may help to normalize intestinal barrier dysfunction observed in patients with IBD. Furthermore, our data provide additional insight into the potential mechanisms through which rifaximin elicits its clinical efficacy in the treatment of IBD.

Topics: Animals; Caco-2 Cells; Cell Movement; Colitis; Colon; Dextran Sulfate; Diphosphonates; Disease Models, Animal; Epithelial Cells; Gastrointestinal Agents; Humans; Intestinal Mucosa; Male; Mice; Mice, Inbred C57BL; p38 Mitogen-Activated Protein Kinases; Pregnane X Receptor; Pregnenolone Carbonitrile; Receptors, Steroid; Rifampin; Rifamycins; Rifaximin; Signal Transduction; Time Factors; Wound Healing

Multidrug-resistant Acinetobacter baumannii becomes an increasing challenge due to the overuse of antibiotics. Combination therapies are considered as effective options to overcome this matter. The present study was to investigate the synergistic activity of meropenem combined with other antibiotics in vitro and in vivo. Checkerboard assay and time-kill assay were performed to study the combination effects in vitro. For the animal model, a murine sepsis model injected with inoculums intraperitoneally was used. Susceptibility test showed that all the twelve strains in this study were resistant to most of the antibiotics except rifampicin. In combination, meropenem plus rifampicin exhibited synergistic activity against six of twelve strains. In the sepsis model, meropenem monotherapy had no therapeutic effect in this model while it can enhance the activity of rifampicin in both survival rate and bacterial clearance from blood. Moreover, combination therapy significantly reduced plasma IL-6 levels compared with rifampicin monotherapy. Pharmacokinetic analysis of rifampicin was also performed in this study. These data above showed that there was synergistic activity between meropenem and rifampicin against multidrug-resistant Acinetobacter baumannii both in vitro and for experimental model of sepsis. It suggested that combining meropenem with rifampicin may be appropriate in treating multidrug-resistant Acinetobacter baumannii infections.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Resistance, Multiple, Bacterial; Drug Synergism; Humans; Male; Meropenem; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Rifampin; Sepsis; Thienamycins; Treatment Outcome

Structure based drug design was used to develop a compound library of novel 2,5,6- and 2,5,7-trisubstituted benzimidazoles. Three structural analogs, SB-P1G10, SB-P8B2 and SB-P3G2 were selected from this library for advanced study. In vitro studies revealed that SB-P8B2 and SB-P3G2 had sigmoidal kill-curves while in contrast SB-P1G10 showed a narrow zonal susceptibility. The in vitro studies also demonstrated that exposure to SB-P8B2 or SB-P3G2 was bactericidal, while SB-P1G10 treatment never resulted in complete killing. The dose curves for the three compounds against clinical isolates were comparable to their respective dose curves in the laboratory strain of Mycobacterium tuberculosis. SB-P8B2 and SB-P3G2 exhibited antibacterial activity against non-replicating bacilli under low oxygen conditions. SB-P3G2 and SB-P1G10 were assessed in acute short-term animal models of tuberculosis, which showed that SB-P3G2 demonstrated activity against M. tuberculosis. Together, these studies reveal an in vitro-in vivo relationship of the 2,5,6-trisubstituted benzimidazoles that serves as a criterion for advancing this class of cell division inhibitors into more resource intensive in vivo efficacy models such as the long-term murine model of tuberculosis and Pre-IND PK/PD studies. Specifically, these studies are the first demonstration of efficacy and an in vitro-in vivo activity relationship for 2,5,6-trisubstituted benzimidazoles. The in vivo activity presented in this manuscript substantiates this class of cell division inhibitors as having potency and efficacy against M. tuberculosis.

Topics: Animals; Antitubercular Agents; Benzimidazoles; Cell Division; Disease Models, Animal; Drug Combinations; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Oxygen; Rifampin; Tuberculosis

The antimicrobial treatment of Stenotrophomonas maltophilia infections is complicated by intrinsic multidrug resistance and a lack of reliable susceptibility data. We assessed the activity of colistin (COL), rifampicin (RIF) and tigecycline (TGC) alone and in combination using a range of in vitro susceptibility testing methodologies and a simple invertebrate model of S. maltophilia infection (Galleria mellonella). Synergy [fractional inhibitory concentration indices (FICIs) ≤0.5] between COL and either RIF or TGC was observed against 92 % and 88 % of 25 S. maltophilia isolates, respectively, despite resistance to one or another of the single agents alone. In time-kill assays, COL combined with either RIF or TGC was superior to single agents, but only the COL/RIF regimen was reliably bactericidal. The in vitro findings correlated with treatment outcomes in G. mellonella, with heightened survival observed for larvae treated with COL/RIF or COL/TGC compared with COL, RIF or TGC alone. COL combined with RIF was the most effective combination overall in both in vitro and in vivo (p < 0.05) assays. Given the difficulty in selecting appropriate therapy for S. maltophilia infections, regimens consisting of COL combined with RIF or TGC could be considered for clinical use.

Topics: Animals; Colistin; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Synergism; Drug Therapy, Combination; Gram-Negative Bacterial Infections; Lepidoptera; Microbial Viability; Minocycline; Rifampin; Stenotrophomonas maltophilia; Survival Analysis; Tigecycline; Treatment Outcome

The repurposing of existing drugs is being pursued as a means by which to accelerate the development of novel regimens for the treatment of drug-susceptible and drug-resistant tuberculosis (TB). In the current study, we assessed the activity of the antipsychotic drug thioridazine (TRZ) in combination with the standard regimen in a well-validated murine TB model. Single-dose and steady-state pharmacokinetic studies were performed in BALB/c mice to establish human-equivalent doses of TRZ. To determine the bactericidal activity of TRZ against TB in BALB/c mice, three separate studies were performed, including a dose-ranging study of TRZ monotherapy and efficacy studies of human-equivalent doses of TRZ with and without isoniazid (INH) or rifampin (RIF). Therapeutic efficacy was assessed by the change in mycobacterial load in the lung. The human-equivalent dose of thioridazine was determined to be 25 mg/kg of body weight, which was well tolerated in mice. TRZ was found to accumulate at high concentrations in lung tissue relative to serum levels. We observed modest synergy during coadministration of TRZ with INH, and the addition of TRZ reduced the emergence of INH-resistant mutants in mouse lungs. In conclusion, this study further illustrates the opportunity to reevaluate the contribution of TRZ to the sterilizing activity of combination regimens to prevent the emergence of drug-resistant M. tuberculosis.

Topics: Animals; Antipsychotic Agents; Antitubercular Agents; Disease Models, Animal; Drug Repositioning; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Female; Isoniazid; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Rifampin; Thioridazine; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary

The need to develop new, improved treatments for tuberculosis (TB) remains urgent, and the repurposing of existing drugs represents a possible shortcut to market. Recently, there has been significant interest in host-directed adjuvant therapy to enhance bacillary killing. HMG-CoA reductase inhibitors (statins), which are among the most commonly prescribed drugs, have immunomodulatory properties and improve the clinical outcomes of bacterial infections.. We studied the tuberculocidal activity of simvastatin alone and in combination with first-line anti-TB drugs in J774 macrophages and during chronic TB infection.. Exposure to 5 μM simvastatin significantly increased the tuberculocidal activity of isoniazid in J774 macrophages at Day 3 after infection versus isoniazid alone (P=0.02). Similarly, relative to the standard oral regimen of rifampicin (10 mg/kg), isoniazid (10 mg/kg) and pyrazinamide (150 mg/kg) given five times weekly, the addition of 25 mg/kg simvastatin enhanced bacillary killing, reducing the number of lung cfu by an additional 1 log10 at Day 28 (P<0.01) and by a further 1.25 log10 at Day 56 (P<0.01).. The potential additive activity of simvastatin to first-line TB treatment holds promise. However, further studies to identify the optimal statin and dosing are required. In addition the ability of combination treatment with statins to accelerate the time required to achieve a stable cure remains to be explored.

Topics: Animals; Antitubercular Agents; Bacterial Load; Cell Line; Colony Count, Microbial; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Female; Isoniazid; Lung; Macrophages; Mice, Inbred BALB C; Pyrazinamide; Rifampin; Simvastatin; Treatment Outcome; Tuberculosis

Acinetobacter baumannii is recognized as an emerging bacterial pathogen because of traits such as prolonged survival in a desiccated state, effective nosocomial transmission, and an inherent ability to acquire antibiotic resistance genes. A pressing need in the field of A. baumannii research is a suitable model strain that is representative of current clinical isolates, is highly virulent in established animal models, and can be genetically manipulated. To identify a suitable strain, a genetically diverse set of recent U.S. military clinical isolates was assessed. Pulsed-field gel electrophoresis and multiplex PCR determined the genetic diversity of 33 A. baumannii isolates. Subsequently, five representative isolates were tested in murine pulmonary and Galleria mellonella models of infection. Infections with one strain, AB5075, were considerably more severe in both animal models than those with other isolates, as there was a significant decrease in survival rates. AB5075 also caused osteomyelitis in a rat open fracture model, while another isolate did not. Additionally, a Tn5 transposon library was successfully generated in AB5075, and the insertion of exogenous genes into the AB5075 chromosome via Tn7 was completed, suggesting that this isolate may be genetically amenable for research purposes. Finally, proof-of-concept experiments with the antibiotic rifampin showed that this strain can be used in animal models to assess therapies under numerous parameters, including survival rates and lung bacterial burden. We propose that AB5075 can serve as a model strain for A. baumannii pathogenesis due to its relatively recent isolation, multidrug resistance, reproducible virulence in animal models, and genetic tractability.. The incidence of A. baumannii infections has increased over the last decade, and unfortunately, so has antibiotic resistance in this bacterial species. A. baumannii is now responsible for more than 10% of all hospital-acquired infections in the United States and has a >50% mortality rate in patients with sepsis and pneumonia. Most research on the pathogenicity of A. baumannii focused on isolates that are not truly representative of current multidrug-resistant strains isolated from patients. After screening of a panel of isolates in different in vitro and in vivo assays, the strain AB5075 was selected as more suitable for research because of its antibiotic resistance profile and increased virulence in animal models. Moreover, AB5075 is susceptible to tetracycline and hygromycin, which makes it amenable to genetic manipulation. Taken together, these traits make AB5075 a good candidate for use in studying virulence and pathogenicity of this species and testing novel antimicrobials.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Infective Agents; Disease Models, Animal; Electrophoresis, Gel, Pulsed-Field; Female; Genome, Bacterial; Mice; Moths; Phylogeny; Rifampin; Virulence

We recently reported that in lung tissue, thioridazine accumulates at high concentrations relative to serum levels, displaying modest synergy with isoniazid and reducing the emergence of isoniazid-resistant mutants in mouse lungs. In this study, we sought to investigate the sterilizing activity of human-equivalent doses of thioridazine when given in combination with the "Denver regimen" against acute murine tuberculosis. We found a trend toward a positive impact of thioridazine on the bacterial clearance and lowering relapse rates of the combined standard TB chemotherapy.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Therapy, Combination; Female; Isoniazid; Lung; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Thioridazine; Tuberculosis, Pulmonary

To evaluate in vitro and in vivo efficacies of linezolid, vancomycin, and the combination of linezolid and rifampicin against two Staphylococcus aureus strains with reduced susceptibility to beta-lactams and one of them also to glycopeptides.. In vitro killing curves and a rabbit model: Meningitis was induced by intracisternal inoculation of 10(8) CFU/ml of each strain. Five hours later (0 h), rabbits were randomly assigned to control or to therapeutic groups. CSF bacterial counts, lactate and protein concentrations, and pharmacokinetic parameters were determined.. In vivo: linezolid and its combination with rifampicin reduced bacterial concentrations at 24 h, median cfu/mL 4.85 vs 3.87 (p < 0.05) for linezolid and 5.02 vs 4.21 (p < 0.05) for linezolid + rifampicin, against the glycopeptide intermediate S. aureus (GISA) strain and improved inflammatory parameters.. Despite the need for more experimental data, our results suggest that linezolid and its combinations could be considered as a potential alternative in difficult-to-treat CNS infections and especially in those due to GISA strains and deserve more studies.

Topics: Acetamides; Animals; Anti-Bacterial Agents; beta-Lactam Resistance; beta-Lactams; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Female; Glycopeptides; Linezolid; Meningitis, Bacterial; Microbial Sensitivity Tests; Oxazolidinones; Rabbits; Random Allocation; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Vancomycin

A mouse model was developed for in vivo monitoring of infection and the effect of antimicrobial treatment against Staphylococcus aureus biofilms, using the [(18)F]fluoro-deoxyglucose-MicroPET ([(18)F]FDG-MicroPET) image technique. In the model, sealed Vialon catheters were briefly precolonized with S. aureus strains ATCC 15981 or V329, which differ in cytotoxic properties and biofilm matrix composition. After subcutaneous implantation of catheters in mice, the S. aureus strain differences found in bacterial counts and the inflammatory reaction triggered were detected by the regular bacteriological and histological procedures and also by [(18)F]FDG-MicroPET image signal intensity determinations in the infection area and regional lymph node. Moreover, [(18)F]FDG-MicroPET imaging allowed the monitoring of the rifampin treatment effect, identifying the periods of controlled infection and those of reactivated infection due to the appearance of bacteria naturally resistant to rifampin. Overall, the mouse model developed may be useful for noninvasive in vivo determinations in studies on S. aureus biofilm infections and assessment of new therapeutic approaches.

Topics: Animals; Anti-Bacterial Agents; Bacterial Adhesion; Biofilms; Catheters, Indwelling; Disease Models, Animal; Female; Fluorodeoxyglucose F18; Mice; Microbial Sensitivity Tests; Positron-Emission Tomography; Radiopharmaceuticals; Rifampin; Staphylococcal Infections; Staphylococcus aureus

The bicyclic nitroimidazole-like molecule PA-824 has activity both against replicating and hypoxic non-replicating Mycobacterium tuberculosis, raising the possibility that it may have a role in the treatment of latent tuberculosis infection (LTBI). This study aimed to examine the bactericidal and sterilising activities of PA-824 against LTBI in C3HeB/FeJ mice, which develop hypoxic, necrotic granulomas histologically resembling their human counterparts. Female 5-6-week-old C3HeB/FeJ mice were immunised via the aerosol route with a recombinant BCG strain overexpressing the 30-kDa major secretory protein (rBCG30) and were aerosol-infected 6 weeks later with virulent M. tuberculosis H37Rv. Six weeks after M. tuberculosis infection, separate groups of mice were left untreated (negative controls) or were treated with either rifampicin, isoniazid (INH) or PA-824. Culture-positive relapse was assessed in subgroups of mice after 2 months and 4 months of treatment. Human-equivalent doses of PA-824 given five times weekly showed similar bactericidal activity as INH at Months 1, 2 and 4 of treatment, and 15/15 mice treated with either PA-824 or INH showed lung-culture relapse 3 months after completion of treatment. To the best of our knowledge, this is the first report examining the sterilising activity of PA-824 in an animal model of LTBI. This model may be useful for screening the efficacy of novel drugs against LTBI, particularly those with specific activity against bacilli residing within necrotic lung granulomas.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Female; Isoniazid; Latent Tuberculosis; Lung; Mice; Mice, Inbred C3H; Mycobacterium tuberculosis; Nitroimidazoles; Rifampin

Thioridazine, a potent phenothiazine compound was evaluated for its chemotherapeutic efficacy against experiment model of tuberculosis. Thioridazine potentiated the activities of both isoniazid and rifampicin (>1 log CFU reduction) against the in vitro latent Mycobacterium tuberculosis bacilli. Further, a murine model of latent tuberculosis was used and the standard 9-month isoniazid and 4-month rifampicin regimen along with thioridazine as an adjunct drug were evaluated. Thioridazine led to an accelerated clearance of bacilli with both the regimen, thereby leading to completion of therapy much earlier than the standard end-point. In the case of 9-month isoniazid regimen, when thioridazine was used along with isoniazid as an adjunct drug, complete clearance was observed as early as 24 weeks as compared to the 36 week standard isoniazid monotherapy regimen. Also, in the 4-month rifampicin regimen, it was observed that the bacillary clearance was more robust when rifampicin was used along with thioridazine (>3 log CFU reduction) than rifampicin alone (>2 log CFU reduction). Our findings implicate that thioridazine, when used as an adjunct drug along with isoniazid or rifampicin has the potential to augment their chemotherapeutic efficacy against experimental latency.

Topics: Animals; Antitubercular Agents; Colony Count, Microbial; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Female; Isoniazid; Latent Tuberculosis; Male; Mice; Microbial Sensitivity Tests; Microbial Viability; Mycobacterium tuberculosis; Rifampin; Thioridazine

During tuberculosis (TB), some Mycobacterium tuberculosis bacilli persist in the presence of an active immunity and antibiotics that are used to treat the disease. Herein, by using the Cornell model of TB persistence, we further explored our recent finding that suggested that M. tuberculosis can escape therapy by residing in the bone marrow (BM) mesenchymal stem cells. We initially showed that M. tuberculosis rapidly disseminates to the mouse BM after aerosol exposure and maintained a stable burden for at least 220 days. In contrast, in the lungs, the M. tuberculosis burden peaked at 28 days and subsequently declined approximately 10-fold. More important, treatment of the mice with the antibiotics rifampicin and isoniazid, as expected, resulted in effective clearance of M. tuberculosis from the lungs and spleen. In contrast, M. tuberculosis persisted, albeit at low numbers, in the BM of antibiotic-treated mice. Moreover, most viable M. tuberculosis was recovered from the bone marrow CD271(+)CD45(-)-enriched cell fraction, and only few viable bacteria could be isolated from the CD271(-)CD45(+) cell fraction. These results clearly show that BM mesenchymal stem cells provide an antibiotic-protective niche for M. tuberculosis and suggest that unraveling the mechanisms underlying this phenomenon will enhance our understanding of M. tuberculosis persistence in treated TB patients.

Topics: Adapalene; Animals; Anti-Bacterial Agents; Antitubercular Agents; Bone Marrow; Bone Marrow Cells; Disease Models, Animal; Drug Resistance, Bacterial; Female; Humans; Isoniazid; Leukocyte Common Antigens; Lung; Mesenchymal Stem Cells; Mice; Mice, Inbred C57BL; Mycobacterium tuberculosis; Naphthalenes; Rifampin; Spleen; Tuberculosis

Assessment of the activity of thioridazine towards Mycobacterium tuberculosis (Mtb), in vitro and in vivo as a single drug and in combination with tuberculosis (TB) drugs.. The in vitro activity of thioridazine as single drug or in combination with TB drugs was assessed in terms of MIC and by use of the time-kill kinetics assay. Various Mtb strains among which the Beijing genotype strain BE-1585 were included. In vivo, mice with TB induced by BE-1585 were treated with a TB drug regimen with thioridazine during 13 weeks. Therapeutic efficacy was assessed by the change in mycobacterial load in the lung, spleen and liver during treatment and 13 weeks post-treatment.. In vitro, thioridazine showed a concentration-dependent and time-dependent bactericidal activity towards both actively-replicating and slowly-replicating Mtb. Thioridazine at high concentrations could enhance the activity of isoniazid and rifampicin, and in case of isoniazid resulted in elimination of mycobacteria and prevention of isoniazid-resistant mutants. Thioridazine had no added value in combination with moxifloxacin or amikacin. In mice with TB, thioridazine was poorly tolerated, limiting the maximum tolerated dose (MTD). The addition of thioridazine at the MTD to an isoniazid-rifampicin-pyrazinamide regimen for 13 weeks did not result in enhanced therapeutic efficacy.. Thioridazine is bactericidal towards Mtb in vitro, irrespective the mycobacterial growth rate and results in enhanced activity of the standard regimen. The in vitro activity of thioridazine in potentiating isoniazid and rifampicin is not reflected by improved therapeutic efficacy in a murine TB-model.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Combinations; Drug Therapy, Combination; Female; Isoniazid; Mice, Inbred BALB C; Microbial Sensitivity Tests; Microbial Viability; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Stem Cells; Thioridazine; Tuberculosis

A pharmacophore-based search led to the identification of thiazolopyridine ureas as a novel scaffold with antitubercular activity acting through inhibition of DNA Gyrase B (GyrB) ATPase. Evaluation of the binding mode of thiazolopyridines in a Mycobacterium tuberculosis (Mtb) GyrB homology model prompted exploration of the side chains at the thiazolopyridine ring C-5 position to access the ribose/solvent pocket. Potent compounds with GyrB IC50 ≤ 1 nM and Mtb MIC ≤ 0.1 μM were obtained with certain combinations of side chains at the C-5 position and heterocycles at the C-6 position of the thiazolopyridine core. Substitutions at C-5 also enabled optimization of the physicochemical properties. Representative compounds were cocrystallized with Streptococcus pneumoniae (Spn) ParE; these confirmed the binding modes predicted by the homology model. The target link to GyrB was confirmed by genetic mapping of the mutations conferring resistance to thiazolopyridine ureas. The compounds are bactericidal in vitro and efficacious in vivo in an acute murine model of tuberculosis.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; DNA Gyrase; Dose-Response Relationship, Drug; Mice; Mice, Inbred BALB C; Models, Molecular; Molecular Structure; Mycobacterium tuberculosis; Pyridines; Structure-Activity Relationship; Topoisomerase II Inhibitors; Tuberculosis; Urea

Since 2004, treatment of Mycobacterium ulcerans disease, or Buruli ulcer, has shifted from surgery to daily treatment with streptomycin (STR) + rifampin (RIF) for 8 weeks. For shortening treatment duration, we tested the potential of daily rifapentine (RPT), a long-acting rifamycin derivative, as a substitute for RIF.. BALB/c mice were infected with M. ulcerans in the right hind footpad and treated either daily (7/7) with STR+RIF or five days/week (5/7) with STR+RIF or STR+RPT for 4 weeks, beginning 28 days after infection when CFU counts were 4.88±0.51. The relative efficacy of the drug treatments was compared by footpad CFU counts during treatment and median time to footpad swelling after treatment cessation as measure of sterilizing activity. All drug treatments were bactericidal. After 1 week of treatment, the decline in CFU counts was significantly greater in treated mice but not different between the three treated groups. After 2 weeks of treatment, the decline in CFU was greater in mice treated with STR+RPT 5/7 than in mice treated with STR+RIF 7/7 and STR+RIF 5/7. After 3 and 4 weeks of treatment, CFU counts were nil in mice treated with STR+RPT and reduced by more than 3 and 4 logs in mice treated with STR+RIF 5/7 and STR+RIF 7/7, respectively. In sharp contrast to the bactericidal activity, the sterilizing activity was not different between all drug regimens although it was in proportion to the treatment duration.. The better bactericidal activity of daily STR+RIF and especially of STR+RPT did not translate into better prevention of relapse, possibly because relapse-freecure after treatment of Buruli ulcer is more related to the reversal of mycolactone-induced local immunodeficiency by drug treatment rather than to the bactericidal potency of drugs.

Topics: Animals; Anti-Bacterial Agents; Bacterial Load; Buruli Ulcer; Colony Count, Microbial; Disease Models, Animal; Drug Therapy, Combination; Female; Mice; Mice, Inbred BALB C; Microbial Viability; Mycobacterium ulcerans; Rifampin; Secondary Prevention; Streptomycin; Treatment Outcome

To assess the efficacy of rifampicin in achieving clinical and haematological recovery and clearing infection in dogs with experimentally induced acute monocytic ehrlichiosis.. Five Ehrlichia canis-infected Beagle dogs were treated with rifampicin (10 mg/kg/24 h orally for 3 weeks), nine E. canis-infected dogs received no treatment (infected untreated dogs) and two dogs served as uninfected controls. Clinical score, platelet counts, immunofluorescent antibody titres and PCR detection of E. canis-specific DNA in blood, bone marrow and spleen aspirates were evaluated on post-inoculation days 21 (start of rifampicin), 42 (end of rifampicin) and 98 (end of the study).. By day 21 post-inoculation, all infected dogs became clinically ill and thrombocytopenic, seroconverted and were PCR positive in at least one tissue. Clinical scores and antibody titres did not differ between the treated and infected untreated dogs throughout the study. The rifampicin-treated dogs experienced an earlier resolution of their thrombocytopenia (Kaplan-Meier survival plot, P=0.048), and the median platelet counts were significantly higher in the treated compared with the infected untreated dogs on post-inoculation days 42 (P=0.0233) and 98 (P=0.0195). At the end of the study, three treated and six untreated infected dogs remained PCR positive in one tissue each.. The rifampicin treatment regimen applied in this study hastened haematological recovery, but was inconsistent in eliminating the acute E. canis infection.

Topics: Animals; Anti-Bacterial Agents; Bacterial Load; Blood; Bone Marrow; Disease Models, Animal; Dog Diseases; Dogs; Ehrlichia canis; Ehrlichiosis; Female; Male; Rifampin; Severity of Illness Index; Spleen; Treatment Outcome

Mycobacterium ulcerans infection causes a neglected tropical disease known as Buruli ulcer that is now found in poor rural areas of West Africa in numbers that sometimes exceed those reported for another significant mycobacterial disease, leprosy, caused by M. leprae. Unique among mycobacterial diseases, M. ulcerans produces a plasmid-encoded toxin called mycolactone (ML), which is the principal virulence factor and destroys fat cells in subcutaneous tissue. Disease is typically first manifested by the appearance of a nodule that eventually ulcerates and the lesions may continue to spread over limbs or occasionally the trunk. The current standard treatment is 8 weeks of daily rifampin and injections of streptomycin (RS). The treatment kills bacilli and wounds gradually heal. Whether RS treatment actually stops mycolactone production before killing bacilli has been suggested by histopathological analyses of patient lesions. Using a mouse footpad model of M. ulcerans infection where the time of infection and development of lesions can be followed in a controlled manner before and after antibiotic treatment, we have evaluated the progress of infection by assessing bacterial numbers, mycolactone production, the immune response, and lesion histopathology at regular intervals after infection and after antibiotic therapy. We found that RS treatment rapidly reduced gross lesions, bacterial numbers, and ML production as assessed by cytotoxicity assays and mass spectrometric analysis. Histopathological analysis revealed that RS treatment maintained the association of the bacilli with (or within) host cells where they were destroyed whereas lack of treatment resulted in extracellular infection, destruction of host cells, and ultimately lesion ulceration. We propose that RS treatment promotes healing in the host by blocking mycolactone production, which favors the survival of host cells, and by killing M. ulcerans bacilli.

Topics: Animals; Anti-Bacterial Agents; Bacterial Load; Buruli Ulcer; Cell Survival; Disease Models, Animal; Histocytochemistry; Macrolides; Mass Spectrometry; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Rifampin; Streptomycin

The dosage of 10 mg/kg/d rifampin, as currently used in the treatment of tuberculosis (TB), is not an optimal dose. Shortening of treatment duration might be achievable using an increased rifampin dose.. Determination of optimal rifampin dosage in mice, resulting in maximum therapeutic effect and without adverse effects. Assessment of associated pharmacokinetic parameters and pharmacokinetic/pharmacodynamic indices.. A murine TB infection using a Beijing genotype Mycobacterium tuberculosis strain was established by intratracheal bacterial instillation followed by proper inhalation, while keeping mice in a vertical position. We assessed dose-dependent activity of rifampin in single-drug treatment during 3 weeks. The maximum tolerated dosage, pharmacokinetic parameters, and pharmacokinetic/pharmacodynamic index were determined. Therapeutic efficacy of a range of rifampin (R) dosages added to a regimen of isoniazid (H) and pyrazinamide (Z) was assessed.. Maximum tolerated dosage of rifampin in the murine TB was 160 mg/kg/d. Pharmacokinetic measurement in HR(10)Z and HR(160)Z therapy regimens showed for rifampin a C(max) of 16.2 and 157.3 mg/L, an AUC(0-24h) of 132 and 1,782 h·mg/L, and AUC(0-24h)/minimum inhibitory concentration ratios of 528 and 7129, respectively. A clear dose-effect correlation was observed for rifampin after 3-week single-drug treatment. Administration of HR(80)Z allowed 9-week treatment duration to be effective without relapse of infection.. Our findings indicate that the currently used rifampin dosage in the therapy of TB is too low. In our murine TB model a rifampin dosage of 80 mg/kg/d enabled a significant reduction in therapy duration without adverse effects.

Topics: Animals; Antibiotics, Antitubercular; Area Under Curve; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Maximum Tolerated Dose; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Rifampin; Treatment Outcome; Tuberculosis

Shortening tuberculosis treatment could significantly improve patient adherence and decrease the development of drug resistance. Phosphodiesterase inhibitors (PDE-Is) have been shown to be beneficial in animal models of tuberculosis. We assessed the impact of PDE-Is on the duration of treatment in tuberculous mice.. We analyzed the time to death in Mycobacterium tuberculosis-infected mice receiving type 4 PDE-Is (rolipram and cilomilast) and the impact on bacterial burden, time to clearance, and relapse when types 3 and 5 PDE-Is (cilostazol and sildenafil, respectively) and rolipram were added to the standard treatment. We investigated pharmacokinetic interactions between PDE-Is (cilostazol and sildenafil) and rifampin.. The type 4 PDE-Is rolipram and cilomilast accelerated the time to death in tuberculous mice. The addition of rolipram to standard tuberculosis treatment increased bacterial burden and did not decrease the time to bacterial clearance in the lung, while the addition of the cilostazol and sildenafil reduced the time to clearance by 1 month. Cilostazol and sildenafil did not have negative pharmacokinetic interactions with rifampin.. Type 4 PDE-Is may increase the severity of tuberculosis and should be carefully investigated for use in patients with latent or active tuberculosis. Cilostazol and sildenafil may benefit tuberculosis patients by shortening the duration of therapy.

Topics: Animals; Antitubercular Agents; Bacterial Load; Cilostazol; Disease Models, Animal; Drug Interactions; Humans; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Phosphodiesterase Inhibitors; Piperazines; Purines; Rifampin; Rolipram; Sildenafil Citrate; Sulfones; Survival Analysis; Tetrazoles; Treatment Outcome; Tuberculosis

Recent advances in rational adjuvant design and antigen selection have enabled a new generation of vaccines with potential to treat and prevent infectious disease. The aim of this study was to assess whether therapeutic immunization could impact the course of Mycobacterium tuberculosis infection with use of a candidate tuberculosis vaccine antigen, ID93, formulated in a synthetic nanoemulsion adjuvant, GLA-SE, administered in combination with existing first-line chemotherapeutics rifampicin and isoniazid.. We used a mouse model of fatal tuberculosis and the established cynomolgus monkey model to design an immuno-chemotherapeutic strategy to increase long-term survival and reduce bacterial burden, compared with standard antibiotic chemotherapy alone.. This combined approach induced robust and durable pluripotent antigen-specific T helper-1-type immune responses, decreased bacterial burden, reduced the duration of conventional chemotherapy required for survival, and decreased M. tuberculosis-induced lung pathology, compared with chemotherapy alone.. These results demonstrate the ability of therapeutic immunization to significantly enhance the efficacy of chemotherapy against tuberculosis and other infectious diseases, with implications for treatment duration, patient compliance, and more optimal resource allocation.

Topics: Adjuvants, Immunologic; Animals; Antigens, Bacterial; Antitubercular Agents; Bacterial Proteins; Chemotherapy, Adjuvant; Disease Models, Animal; Female; Isoniazid; Lung; Macaca fascicularis; Mice; Mice, Inbred C57BL; Mycobacterium tuberculosis; Rifampin; Secondary Prevention; Survival Analysis; Time Factors; Tuberculosis Vaccines; Tuberculosis, Pulmonary; Vaccination

The efficacy of daptomycin, imipenem, or rifampin with fosfomycin was evaluated and compared with that of daptomycin-rifampin in a tissue cage model infection caused by methicillin-resistant Staphylococcus aureus (MRSA). Strain HUSA 304 was used. The study yielded the following results for MICs (in μg/ml): fosfomycin, 4; daptomycin, 1; imipenem, 0.25; and rifampin, 0.03. The study yielded the following results for minimum bactericidal concentration (MBC) (in μg/ml): fosfomycin, 8; daptomycin, 4; imipenem, 32; and rifampin, 0.5. Daptomycin-rifampin was confirmed as the most effective therapy against MRSA foreign-body infections. Fosfomycin combinations with high doses of daptomycin and rifampin were efficacious alternative therapies in this setting. Fosfomycin-imipenem was relatively ineffective and did not protect against resistance.

Topics: Animals; Anti-Bacterial Agents; Colony Count, Microbial; Daptomycin; Disease Models, Animal; Drug Combinations; Drug Resistance, Bacterial; Foreign-Body Reaction; Fosfomycin; Imipenem; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Rats; Rats, Wistar; Rifampin; Staphylococcal Infections

To assess the hepatoprotective effect of Solanum xanthocarpum (S. xanthocarpum) fruit extract against antitubercular drug-induced liver toxicity in experimental animals.. Ethanolic (50%) fruit extract of S. xanthocarpum (100, 200 and 400 mg/kg bw) was administered daily for 35 days in experimental animals. Liver toxicity was induced by combination of three antitubercular drugs [isoniazid (I) 7.5 mg/kg, rifampicin (R) 10 mg/kg and pyrazinamide (P) 35 mg/kg] given orally as suspension for 35 days in rats. The hepatoprotective activity was assessed using various biochemical parameters like aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatise (ALP), total bilirubin (TBL), albumin (ALB), total protein (TP), lactate dehydroginase (LDH), and serum cholesterol (CHL). Meanwhile, in vivo antioxidant activities as lipid peroxidation (LPO), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were measured in rat liver homogenate. The biochemical observations were supplemented by histopathological examination.. The results demonstrated that treatment with S. xanthocarpum significantly (P<0.05-P<0.001) and dose-dependently prevented drug induced increase in serum levels of hepatic enzymes. Furthermore, S. xanthocarpum significantly (up to P<0.001) reduced the LPO in the liver tissue and restored activities of defence antioxidant enzymes GSH, SOD and CAT towards normal levels. Histopathology of the liver tissue showed that S. xanthocarpum attenuated the hepatocellular necrosis and led to reduction in inflammatory cells infiltration.. The results of this study strongly indicate the protective effect of S. xanthocarpum against liver injury which may be attributed to its hepatoprotective activity, and thereby scientifically support its traditional use.

Topics: Animals; Antitubercular Agents; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Female; Fruit; Gastrointestinal Agents; Histocytochemistry; Isoniazid; Liver; Liver Function Tests; Male; Mice; Plant Extracts; Plasma; Pyrazinamide; Rats, Wistar; Rifampin; Solanum

We investigated the efficacy of tigecycline and rifampin alone or combined in preventing ureteral stent infection due to Enterococcus faecalis.. The activities of the two antibiotics were previously studied in vitro in absence or in presence of biofilm. For in vivo research, the study included a control group without bacterial challenge to evaluate the sterility of surgical procedure, a challenged control group that did not receive any antibiotic prophylaxis and, for each bacterial strain, three challenged groups that received: (1) 2 mg/kg intraperitoneal tigecycline, immediately after stent implantation; (2) rifampin-coated ureteral stents where 0.2 cm(2) sterile ureteral stents were incubated in 10 mg/L rifampin solution for 30 min immediately before implantation; and (3) intraperitoneal tigecycline plus rifampin-coated ureteral stent at the above concentrations. Ureteral stents were explanted at d 5 following implantation and biofilm bacteria enumerated.. The in vitro studies showed that the biofilm was strongly affected by the presence of rifampin and, in its presence, tigecycline had MICs and MBCs lower than those obtained in the absence of rifampin. Intraperitoneal tigecycline exerted stronger effect than rifampin on bacterial numbers. The combination rifampin plus tigecycline showed efficacies higher than that of each single compound.. These results highlight the potential usefulness of tigecycline in preventing enterococcal ureteral stent infections and the role of rifampin as an interesting antibiotic enhancer.

Topics: Animals; Anti-Bacterial Agents; Antibiotic Prophylaxis; Biofilms; Disease Models, Animal; Drug Therapy, Combination; Enterococcus faecalis; Female; Gram-Positive Bacterial Infections; In Vitro Techniques; Minocycline; Rats; Rats, Wistar; Rifampin; Stents; Tigecycline; Treatment Outcome; Ureter

Standard antituberculosis (anti-TB) therapy requires the use of multiple drugs for a minimum of 6 months, with variable outcomes that are influenced by a number of microbiological, pathological, and clinical factors. This is despite the availability of antibiotics that have good activity against Mycobacterium tuberculosis in vitro and favorable pharmacokinetic profiles in plasma. However, little is known about the distribution of widely used antituberculous agents in the pulmonary lesions where the pathogen resides. The rabbit model of TB infection was used to explore the hypothesis that standard drugs have various abilities to penetrate lung tissue and lesions and that adequate drug levels are not consistently reached at the site of infection. Using noncompartmental and population pharmacokinetic approaches, we modeled the rate and extent of distribution of isoniazid, rifampin, pyrazinamide, and moxifloxacin in rabbit lung and lesions. Moxifloxacin reproducibly showed favorable partitioning into lung and granulomas, while the exposure of isoniazid, rifampin, and pyrazinamide in lesions was markedly lower than in plasma. The extent of penetration in lung and lesions followed different trends for each drug. All four agents distributed rapidly from plasma to tissue with equilibration half-lives of less than 1 min to an hour. The models adequately described the plasma concentrations and reasonably captured actual lesion concentrations. Though further refinement is needed to accurately predict the behavior of these drugs in human subjects, our results enable the integration of lesion-specific pharmacokinetic-pharmacodynamic (PK-PD) indices in clinical trial simulations and in in vitro PK-PD studies with M. tuberculosis.

Topics: Animals; Antitubercular Agents; Aza Compounds; Biological Availability; Disease Models, Animal; Drug Administration Schedule; Female; Fluoroquinolones; Granuloma; Humans; Isoniazid; Lung; Moxifloxacin; Mycobacterium tuberculosis; Pyrazinamide; Quinolines; Rabbits; Rifampin; Tissue Extracts; Tuberculosis, Pulmonary

In preclinical testing of antituberculosis drugs, laboratory-adapted strains of Mycobacterium tuberculosis are usually used both for in vitro and in vivo studies. However, it is unknown whether the heterogeneity of M. tuberculosis stocks used by various laboratories can result in different outcomes in tests of antituberculosis drug regimens in animal infection models. In head-to-head studies, we investigated whether bactericidal efficacy results in BALB/c mice infected by inhalation with the laboratory-adapted strains H37Rv and Erdman differ from each other and from those obtained with clinical tuberculosis strains. Treatment of mice consisted of dual and triple drug combinations of isoniazid (H), rifampin (R), and pyrazinamide (Z). The results showed that not all strains gave the same in vivo efficacy results for the drug combinations tested. Moreover, the ranking of HRZ and RZ efficacy results was not the same for the two H37Rv strains evaluated. The magnitude of this strain difference also varied between experiments, emphasizing the risk of drawing firm conclusions for human trials based on single animal studies. The results also confirmed that the antagonism seen within the standard HRZ regimen by some investigators appears to be an M. tuberculosis strain-specific phenomenon. In conclusion, the specific identity of M. tuberculosis strain used was found to be an important variable that can change the apparent outcome of in vivo efficacy studies in mice. We highly recommend confirmation of efficacy results in late preclinical testing against a different M. tuberculosis strain than the one used in the initial mouse efficacy study, thereby increasing confidence to advance potent drug regimens to clinical trials.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Therapy, Combination; Female; Humans; Isoniazid; Lung; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Treatment Outcome; Tuberculosis, Pulmonary

Combination chemotherapy with rifampin and streptomycin (RIF-STR) for 8 weeks is currently recommended by the WHO as the first-line treatment for Mycobacterium ulcerans infection (Buruli ulcer). To gain better insight into the mode of action of these antibiotics against established M. ulcerans infection foci and to characterize recovery of local immune responses during chemotherapy, we conducted a detailed histopathological study of M. ulcerans-infected and RIF-STR-treated mice. Mice were inoculated with M. ulcerans in the footpad and 11 weeks later treated with RIF-STR. Development of lesions during the first 11 weeks after infection and subsequent differences in disease progression between RIF-STR-treated and untreated mice were studied. Changes in histopathological features, footpad swelling, and number of CFU were analyzed. After inoculation with M. ulcerans, massive infiltrates dominated by polymorphonuclear leukocytes developed at the inoculation site but did not prevent bacterial multiplication. Huge clusters of extracellular bacteria located in large necrotic areas and surrounded by dead leukocytes developed in the untreated mice. Chemotherapy with RIF-STR led to a rapid drop in CFU associated with loss of solid Ziehl-Neelsen staining of acid-fast bacilli. Development of B-lymphocyte clusters and of macrophage accumulations surrounding the mycobacteria demonstrated the resolution of local immune suppression. Results demonstrate that the experimental M. ulcerans mouse infection model will be a valuable tool to investigate efficacy of new treatment regimens and of candidate vaccines.

Topics: Animals; Anti-Bacterial Agents; Buruli Ulcer; Colony Count, Microbial; Disease Models, Animal; Drug Therapy, Combination; Female; Foot; Humans; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Rifampin; Streptomycin; Treatment Outcome

The aim of this work was to determine the in vitro activity of tigecycline and its bactericidal effect for a large number of Gram-positive cocci, as well as to investigate its in vitro interaction with six clinically used antibiotics. In vivo, a wound model was established through the panniculus carnosus of BALB/c mice, and then inoculated with 5 × 10(7) colony-forming units (CFU) of Staphylococcus aureus or Enterococcus faecalis. For each bacterial strain, the study included an infected or non-infected group that did not receive any treatment, three groups singly treated with tigecycline, rifampin, and daptomycin, and two groups that received tigecycline treatment plus rifampin or daptomycin. In the in vitro studies, tigecycline, daptomycin, and teicoplanin were active against all of the 48 Gram-positive isolates. The combination of tigecycline with rifampicin and daptomycin was synergistic against S. aureus and Enterococcus spp. In the in vivo studies, all groups treated with single drugs showed statistically significant results compared to the control group. The two groups treated with a combination of drugs showed the highest antimicrobial efficacy. In conclusion, our results suggested a strong activity of tigecycline alone and in combination with other antimicrobial agents against multi-resistant Gram-positive organisms isolated from wound infections.

Topics: Animals; Anti-Bacterial Agents; Daptomycin; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Gram-Positive Bacterial Infections; Gram-Positive Cocci; Male; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Minocycline; Rifampin; Surgical Wound Infection; Tigecycline; Treatment Outcome

Multiple system atrophy (MSA) is a neurodegenerative disease caused by α-synuclein (α-syn) accumulation in oligodendrocytes and neurons. We generated a transgenic (Tg) mouse model in which human α-syn was overexpressed in oligodendrocytes. Our previous studies have revealed that oligodendrocytic α-syn inclusions induced neuronal α-syn accumulation, thereby resulting in progressive neuronal degeneration in mice. We also demonstrated that an insoluble complex of α-syn and β-III tubulin in microtubules progressively accumulated in neurons, thereby leading to neuronal degeneration. In the present study, we demonstrated that neuronal accumulation of the insoluble complex was derived from binding of α-syn to β-III tubulin and not from α-syn self-aggregation. Thus, interaction between α-syn and β-III tubulin plays an important role in neuronal α-syn accumulation in an MSA mouse model.

Topics: alpha-Synuclein; Animals; Cells, Cultured; Disease Models, Animal; Humans; Mice; Mice, Transgenic; Multiple System Atrophy; Neurons; Nocodazole; Polymerization; Protein Binding; Rifampin; Tubulin; Tubulin Modulators

Buruli ulcer (BU) is a neglected necrotizing disease of the skin, subcutaneous tissue and bone, caused by Mycobacterium ulcerans. BU pathogenesis is associated with mycolactone, a lipidic exotoxin with cytotoxic and immunosuppressive properties. Since 2004, the World Health Organization recommends the treatment of BU with a combination of rifampicin and streptomycin (RS). Histological analysis of human tissue samples suggests that such antibiotic treatment reverses the mycolactone-induced local immunosuppression, leading to increased inflammatory infiltrations and phagocytosis of bacilli.. We used a mouse model of M. ulcerans footpad infection, followed by combined RS treatment. Time-lapsed analyses of macroscopic lesions, bacterial burdens, histology and immunohistochemistry were performed in footpads. We also performed CFU counts, histology and immunohistochemistry in the popliteal draining lymph nodes (DLN). We observed a shift in the cellular infiltrates from a predominantly neutrophilic/macrophagic to a lymphocytic/macrophagic profile in the infected footpads of antibiotic-treated mice. This shift occurred before the elimination of viable M. ulcerans organisms, which were ultimately eradicated as demonstrated by the administration of dexamethasone. This reduction of bacillary loads was accompanied by an increased expression of inducible nitric oxide synthase (NOS2 or iNOS). Predominantly mononuclear infiltrates persisted in the footpads during and after treatment, coincident with the long persistence of non-viable poorly stained acid-fast bacilli (AFB). We additionally observed that antibiotherapy prevented DLN destruction and lymphocyte depletion, which occurs during untreated experimental infections.. Early RS treatment of M. ulcerans mouse footpad infections results in the rapid elimination of viable bacilli with pathogen eradication. However, non-viable AFB persisted for several months after lesion sterilization. This RS regimen prevented DLN destruction, allowing the rapid re-establishment of local and regional cell mediated immune responses associated with macrophage activation. Therefore it is likely that this re-establishment of protective cellular immunity synergizes with antibiotherapy.

Topics: Animals; Anti-Bacterial Agents; Buruli Ulcer; Dexamethasone; Disease Models, Animal; Disease Progression; Drug Therapy, Combination; Female; Flow Cytometry; Immunity, Cellular; Immunosuppressive Agents; Inflammation; Lymphocytes; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Rifampin; Streptomycin

To compare the efficacy of in situ replacement with rifampicin-soaked silver-coated polyester (RSSCP) to that of expanded polytetrafluoroethylene (ePTFE) graft replacements in a porcine model for early aortic prosthetic vascular graft infection (PVGI).. Sixty pigs received polyester or silver-coated grafts with an 8 mm diameter implanted end-to-end in the infrarenal aorta, and the grafts were inoculated with approximately 10(6)Staphylococcus aureus. All developed S. aureus PVGI. Two weeks later, the 52 surviving pigs were randomised to undergo in situ graft replacement with ePTFE or RSSCP grafts followed by oral administration of 300 mg rifampicin and 750 mg ciprofloxacin twice a day, postoperatively. After three weeks, all pigs were sacrificed. In situ perigraft swabs and graft material were analysed for S. aureus quantitatively.. Only one out of 25 RSSCP grafts were infected with S. aureus, whereas 15 of 27 ePTFE grafts were infected after 3 weeks (OR = 0.022, 95% CI: 0.002, 0.219, P = 0.001).. In situ replacement with RSSCP grafts and oral rifampicin plus ciprofloxacin is more efficiency in eradicating S. aureus PVGI than ePTFE grafts treated with same oral antibiotics in a porcine aortic PVGI model.

Topics: Animals; Anti-Bacterial Agents; Aorta, Abdominal; Biocompatible Materials; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Ciprofloxacin; Device Removal; Disease Models, Animal; Polyesters; Polymers; Polytetrafluoroethylene; Prosthesis-Related Infections; Reoperation; Rifampin; Silver Compounds; Staphylococcal Infections; Staphylococcus aureus; Swine

A key to the success of Mycobacterium tuberculosis (Mtb) is the bacteria's ability to survive and thrive in the presence of numerous stresses mounted by the host. Small, non-coding RNAs (sRNAs) have been shown to modulate numerous stress responses in bacteria, yet to date only two studies have screened the Mtb transcriptome to identify sRNA. Their association with oxidative and acid stress has been demonstrated but the cellular function and role of these sRNAs in the pathogenesis of tuberculosis (TB) remain unknown. Here, we have identified an sRNA, ncrMT1302, in a locus involved in cAMP metabolism and demonstrate that expression of ncrMT1302 responds to changes in pH and cAMP concentration. The differential expression of ncrMT1302 observed in wild-type Mtb during growth is abolished in a strain lacking MT1302, an adenylyl cyclase encoding gene. We report that ncrMT1302 is expressed in Mtb residing in the lungs of mice during an active infection.

Topics: Animals; Cloning, Molecular; Cyclic AMP; Disease Models, Animal; Female; Gene Expression; Humans; Hydrogen-Ion Concentration; Mice; Mycobacterium tuberculosis; Rifampin; RNA, Bacterial; RNA, Small Untranslated; Tuberculosis

Perioperative infection of an aortic graft is one of the most devastating complications of vascular surgery, with a mortality rate of 10% to 30%. The rate of amputation of the lower limbs is generally >25%, depending on the graft material, the location of the graft and infection, and the bacterial virulence. In vitro studies suggest that an antibiotic-impregnated graft may help prevent perioperative graft infection. In a pilot animal study, we tested a locally developed technique of bonding Dacron aortic grafts with three antimicrobial agents to evaluate the ensuing synergistic preventive effect on direct perioperative bacterial contamination.. We surgically implanted a 6-mm vascular knitted Dacron graft in the infrarenal abdominal aorta of six Sinclair miniature pigs. Two pigs received unbonded, uninoculated grafts; two received unbonded, inoculated grafts; and two received inoculated grafts that were bonded with chlorhexidine, rifampin, and minocycline. Before implantation, the two bonded grafts and the two unbonded grafts were immersed for 15 minutes in a 2-mL bacterial solution containing 1 to 2 × 10(7) colony-forming units (CFU)/mL of Staphylococcus aureus (ATCC 29213). Two weeks after graft implantation, the pigs were euthanized, and the grafts were surgically excised for clinical, microbiologic, and histopathologic study.. The two bonded grafts treated with S aureus showed no bacterial growth upon explant, whereas the two unbonded grafts treated with S aureus had high bacterial counts (6.25 × 10(6) and 1.38 × 10(7) CFU/graft). The two control grafts (unbonded and untreated) showed bacterial growth (1.8 × 10(3) and 7.27 × 10(3) CFU/graft) that presumably reflected direct, accidental perioperative bacterial contamination; S cohnii ssp urealyticus and S chromogenes, but not S aureus, were isolated. The histopathologic and clinical data confirmed the microbiologic findings. Only pigs that received unbonded grafts showed histopathologic evidence of a perigraft abscess.. Our results suggest that bonding aortic grafts with this triple antimicrobial combination is a promising method of reducing graft infection resulting from direct postoperative bacterial contamination for at least 2 weeks. Further studies are needed to explore the ability of this novel graft to combat one of the most feared complications in vascular surgery.

Topics: Animals; Anti-Infective Agents; Aorta, Abdominal; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Chlorhexidine; Coated Materials, Biocompatible; Disease Models, Animal; Drug Therapy, Combination; Minocycline; Pilot Projects; Polyethylene Terephthalates; Prosthesis Design; Prosthesis-Related Infections; Rifampin; Staphylococcal Infections; Swine; Swine, Miniature; Time Factors

In previous experiments, replacing the 10-mg/kg of body weight daily dose of rifampin with 7.5 to 10 mg/kg of rifapentine in combinations containing isoniazid and pyrazinamide reduced the duration of treatment needed to cure tuberculosis in BALB/c mice by approximately 50% due to rifapentine's more potent activity and greater drug exposures obtained. In the present study, we performed dose-ranging comparisons of the bactericidal and sterilizing activities of rifampin and rifapentine, alone and in combination with isoniazid and pyrazinamide with or without ethambutol, in BALB/c mice and in C3HeB/FeJ mice, which develop necrotic lung granulomas after infection with Mycobacterium tuberculosis. Each rifamycin demonstrated a significant increase in sterilizing activity with increasing dose. Rifapentine was roughly 4 times more potent in both mouse strains. These results reinforce the rationale for ongoing clinical trials to ascertain the highest well-tolerated doses of rifampin and rifapentine. This study also provides an important benchmark for the efficacy of the first-line regimen in C3HeB/FeJ mice, a strain in which the lung lesions observed after M. tuberculosis infection may better represent the pathology of human tuberculosis.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Disease Models, Animal; Drug Administration Schedule; Drug Therapy, Combination; Ethambutol; Isoniazid; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Pyrazinamide; Random Allocation; Rifampin; Treatment Outcome; Tuberculosis, Pulmonary

With a host of new antitubercular chemotherapeutics in development, methods to assess the activity of these agents beyond mouse efficacy are needed to prioritize combinations for clinical trials. Lesions in Mycobacterium tuberculosis-infected rabbits are hypoxic, with histopathologic features that closely resemble those of human tuberculous lesions. Using [(18)F]2-fluoro-deoxy-d-glucose ([(18)F]FDG) positron emission tomography-computed tomography (PET-CT) imaging, we studied the dynamics of tuberculosis infection in rabbits, revealing an initial inflammatory response followed by a consolidative chronic disease. Five weeks after infection, as much as 23% of total lung volume was abnormal, but this was contained and to some extent reversed naturally by 9 weeks. During development of this chronic state, individual lesions in the same animal had very different fates, ranging from complete resolution to significant progression. Lesions that remained through the initial stage showed an increase in volume and tissue density over time by CT. Initiation of chemotherapy using either isoniazid (INH) or rifampin (RIF) during chronic infection reduced bacterial load with quantitative changes in [(18)F]FDG uptake, lesion density and total lesion volume measured by CT. The [(18)F]FDG PET uptake in lesions was significantly reduced with as little as 1 week of treatment, while the volume and density of lesions changed more slowly. The results from this study suggest that rabbits may be a useful surrogate species for evaluating novel chemotherapies and understanding changes in both PET and CT scans in human clinical trials.

Topics: Animals; Antitubercular Agents; Bacterial Load; Disease Models, Animal; Fluorodeoxyglucose F18; Granuloma; Isoniazid; Lung; Multimodal Imaging; Mycobacterium tuberculosis; Positron-Emission Tomography; Rabbits; Radiopharmaceuticals; Random Allocation; Rifampin; Tomography, X-Ray Computed; Tuberculosis, Pulmonary

To assess the activity of clofazimine (CFZ) against Mycobacterium tuberculosis persisters using an oxygen depletion model and a low-dose aerosol mouse model of chronic tuberculosis (TB).. In in vitro experiments, CFZ showed much better activity than isoniazid under anaerobic conditions. In a low-dose aerosol mouse model of TB, we evaluated the efficacy of CFZ and moxifloxacin at different doses following treatment durations of 30, 60 and 90 days.. CFZ showed significant bactericidal activity in the mouse model over the wide dose range of 2-200 mg/kg. CFZ activity was dose-dependent. The bacilli were eradicated in the CFZ 200 mg/kg group after treatment for 60 days, and in the CFZ 20 mg/kg group after 90 days of treatment.. CFZ exhibits dose-dependent, sustained bactericidal activity against M. tuberculosis persisters, and thus warrants further study to demonstrate its potential to contribute significantly in a novel treatment-shortening regimen.

Topics: Animals; Antitubercular Agents; Aza Compounds; Chronic Disease; Clofazimine; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Resistance, Bacterial; Fluoroquinolones; Isoniazid; Male; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Moxifloxacin; Mycobacterium tuberculosis; Quinolines; Rifampin; Time Factors; Tuberculosis, Pulmonary

Despite great effort by health organizations worldwide in fighting tuberculosis (TB), morbidity and mortality are not declining as expected. One of the reasons is related to the evolutionary development of Mycobacterium tuberculosis, in particular the Beijing genotype strains. In a previous study, we showed the association between the Beijing genotype and an increased mutation frequency for rifampin resistance. In this study, we use a Beijing genotype strain and an East-African/Indian genotype strain to investigate with our mouse TB model whether the higher mutation frequency observed in a Beijing genotype strain is associated with treatment failure particularly during noncompliance therapy. Both genotype strains showed high virulence in comparison to that of M. tuberculosis strain H37Rv, resulting in a highly progressive infection with a rapid lethal outcome in untreated mice. Compliance treatment was effective without relapse of TB irrespective of the infecting strain, showing similar decreases in the mycobacterial load in infected organs and similar histopathological changes. Noncompliance treatment, simulated by a reduced duration and dosing frequency, resulted in a relapse of infection. Relapse rates were correlated with the level of noncompliance and were identical for Beijing infection and East African/Indian infection. However, only in Beijing-infected mice, isoniazid-resistant mutants were selected at the highest level of noncompliance. This is in line with the substantial selection of isoniazid-resistant mutants in vitro in a wide isoniazid concentration window observed for the Beijing strain and not for the EAI strain. These results suggest that genotype diversity of M. tuberculosis may be involved in emergence of resistance and indicates that genotype-tailor-made treatment should be investigated.

Topics: Animals; Antitubercular Agents; Bacterial Typing Techniques; Disease Models, Animal; Drug Administration Schedule; Drug Resistance, Multiple, Bacterial; Female; Genotype; Humans; Isoniazid; Mice; Mice, Inbred BALB C; Mutation Rate; Mycobacterium tuberculosis; Patient Compliance; Recurrence; Rifampin; Species Specificity; Treatment Failure; Tuberculosis, Multidrug-Resistant

Mycobacterium tuberculosis 18b, a streptomycin (STR)-dependent mutant that enters a viable but nonreplicating state in the absence of STR, has been developed as a simple model for drug testing against dormant bacilli. Here, we further evaluated the STR-starved 18b (SS18b) model both in vitro and in vivo by comparing the behavior of 22 approved and experimental tuberculosis drugs. Using the resazurin reduction microplate assay (REMA), rifampin (RIF), rifapentine (RPT), TMC207, clofazimine (CFM), and linezolid (LIN) were found to be active against SS18b in vitro, and their bactericidal activity was confirmed by determining the number of CFU. A latent 18b infection was established in mice, and some of the above-mentioned drugs were used for treatment, either alone or in combination with RIF. RIF, RPT, TMC207, CFM, and pyrazinamide (PZA) were all active in vivo, while cell wall inhibitors were not. A comparative kinetic study of rifamycin efficacy was then undertaken, and the results indicated that RPT clears latent 18b infection in mice faster than RIF. Intrigued by the opposing responses of live and dormant 18b cells to cell wall inhibitors, we conducted a systematic analysis of 14 such inhibitors using REMA. This uncovered an SS18b signature (CWPRED) that accurately predicted the activities of cell wall inhibitors and performed well in a blind study. CWPRED will be useful for establishing the mode of action of compounds with unknown targets, while the SS18b system should facilitate the discovery of drugs for treating latent tuberculosis.

Topics: Acetamides; Amino Acid Sequence; Animals; Antitubercular Agents; Clofazimine; Diarylquinolines; Disease Models, Animal; Drug Discovery; Drugs, Investigational; Female; Genetic Engineering; Latent Tuberculosis; Linezolid; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Molecular Sequence Data; Mycobacterium tuberculosis; Oxazines; Oxazolidinones; Quinolines; Rifampin; Streptomycin; Structure-Activity Relationship; Xanthenes

Buruli ulcer (BU) is a necrotizing disease of the skin, subcutaneous tissue and bone caused by Mycobacterium ulcerans. It has been suggested that the immune response developed during the recommended rifampicin/streptomycin (RS) antibiotherapy is protective, contributing to bacterial clearance. On the other hand, paradoxical reactions have been described during or after antibiotherapy, characterized by pathological inflammatory responses. This exacerbated inflammation could be circumvented by immunosuppressive drugs. Therefore, it is important to clarify if the immune system contributes to bacterial clearance during RS antibiotherapy and if immunosuppression hampers the efficacy of the antibiotic regimen.. We used the M. ulcerans infection footpad mouse model. Corticosteroid-induced immunosuppression was achieved before experimental infection and maintained during combined RS antibiotherapy by the administration of dexamethasone (DEX). Time-lapsed analyses of macroscopic lesions, bacterial burdens, histology and immunohistochemistry were performed in M. ulcerans-infected footpads. We show here that corticosteroid-immunosuppressed mice are more susceptible to M. ulcerans, with higher bacterial burdens and earlier ulceration. Despite this, macroscopic lesions remised during combined antibiotic/DEX treatment and no viable bacteria were detected in the footpads after RS administration. This was observed despite a delayed kinetics in bacterial clearance, associated with a local reduction of T cell and neutrophil numbers, when compared with immunocompetent RS-treated mice. In addition, no relapse was observed following an additional 3 month period of DEX administration.. These findings reveal a major role of the RS bactericidal activity for the resolution of M. ulcerans experimental infections even during immunosuppression, and support clinical investigation on the potential use of corticosteroids or other immunosuppressive/anti-inflammatory drugs for the management of BU patients undergoing paradoxical reactions.

Topics: Adrenal Cortex Hormones; Animals; Anti-Bacterial Agents; Buruli Ulcer; Disease Models, Animal; Female; Foot; Histocytochemistry; Immunohistochemistry; Immunosuppressive Agents; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Rifampin; Streptomycin; Treatment Outcome

The incidence of carbapenem-resistant Acinetobacter baumannii infection is increasing, which might be associated with high morbidity and mortality among critically ill patients with limited therapeutic options. This study was conducted to evaluate the clinical and microbiological features of carbapenem-resistant A. baumannii bacteraemia. The medical records of 28 adult patients with this bacteraemia admitted to Korea University Guro Hospital, from January 2005 through December 2010, were reviewed. Using the 28 bloodstream isolates, we intended to detect genes encoding carbapenemases, and investigate the inoculum effect on each of the antimicrobial agents rifampicin, imipenem, colistin and tigecycline. With one blood isolate from a patient with pneumonia, rifampicin-inducible resistance was examined using the experimental mouse pneumonia model. Out of 28 carbapenem-resistant A. baumannii bloodstream infections (BIs), the most common primary focus was the central venous catheter (35.7 %) and then the lung (32.1 %). The 30 day overall mortality was 53.6 %; in most cases (80 %) the patients died within 10 days after the onset of the bacteraemia. By univariate analysis, inappropriate antimicrobial therapy (73.3 vs 30.8 %, P = 0.02), mechanical ventilation (53.3 vs 15.4 %, P = 0.04) and a high Pitt bacteraemia score (4.9±1.9 vs 2.2±1.2, P<0.01) were statistically significant risk factors for mortality, while only a high Pitt bacteraemia score (odds ratio 2.6; 95 % confidence interval 1.1-6.5) was independently associated with 30 day mortality by multivariate analysis. All 28 isolates had the bla(OXA-51)-like gene with upstream ISAbaI, 2 of which additionally had the bla(OXA-58)-like gene and the bla(OXA-23)-like gene. Inoculum effect and rifampicin inducible resistance were not detected. Considering the rapid progression to death in carbapenem-resistant A. baumannii BIs, early empirical antibiotic therapy would be warranted based on the local microbiological data in each hospital.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Adult; Aged; Animals; Bacteremia; beta-Lactam Resistance; beta-Lactamases; Carbapenems; Disease Models, Animal; Female; Genes, Bacterial; Humans; Male; Mice; Mice, Inbred ICR; Microbial Sensitivity Tests; Middle Aged; Pneumonia, Bacterial; Republic of Korea; Rifampin; Risk Factors

treatment of Mycobacterium ulcerans disease, or Buruli ulcer (BU), has shifted from surgery to treatment with streptomycin(STR)+rifampin(RIF) since 2004 based on studies in a mouse model and clinical trials. We tested two entirely oral regimens for BU treatment, rifampin(RIF)+clarithromycin(CLR) and rifapentine(RPT)+clarithromycin(CLR) in the mouse model.. BALB/c mice were infected in the right hind footpad with M. ulcerans strain 1059 and treated daily (5 days/week) for 4 weeks, beginning 11 days after infection. Treatment groups included an untreated control, STR+RIF as a positive control, and test regimens of RIF, RPT, STR and CLR given alone and the RIF+CLR and RPT+CLR combinations. The relative efficacy of the drug treatments was compared on the basis of footpad CFU counts and median time to footpad swelling. Except for CLR, which was bacteriostatic, treatment with all other drugs reduced CFU counts by approximately 2 or 3 log(10). Median time to footpad swelling after infection was 5.5, 16, 17, 23.5 and 36.5 weeks in mice receiving no treatment, CLR alone, RIF+CLR, RIF alone, and STR alone, respectively. At the end of follow-up, 39 weeks after infection, only 48%, 26.4% and 16.3% of mice treated with RPT+CLR, RPT alone and STR+RIF had developed swollen footpads. An in vitro checkerboard assay showed the interaction of CLR and RIF to be indifferent. However, in mice, co-administration with CLR resulted in a roughly 25% decrease in the maximal serum concentration (Cmax) and area under the serum concentration-time curve (AUC) of each rifamycin. Delaying the administration of CLR by one hour restored Cmax and AUC values of RIF to levels obtained with RIF alone.. these results suggest that an entirely oral daily regimen of RPT+CLR may be at least as effective as the currently recommended combination of injected STR+oral RIF.

Topics: Animals; Anti-Bacterial Agents; Buruli Ulcer; Clarithromycin; Disease Models, Animal; Drug Therapy, Combination; Female; Mice; Mice, Inbred BALB C; Mycobacterium ulcerans; Rifampin; Treatment Outcome

Daily rifapentine plus isoniazid-pyrazinamide in mice infected with Mycobacterium tuberculosis produces cure in 3 months. Whether cure corresponds to latent infection contained by host immunity or true tissue sterilization is unknown.. To determine the length of treatment with rifapentine-isoniazid-pyrazinamide or rifampin-isoniazid-pyrazinamide needed to prevent relapse in immune-deficient mice.. Aerosol-infected BALB/c and nude mice were treated 5 days per week with either 2 months of the rifapentine-based regimen followed by rifapentine-isoniazid up to 12 months or the same regimen with rifampin instead of rifapentine. Cultures of lung homogenates were performed during the first 3 months and then every 3 months. Relapse rates were assessed after 3, 6, 9, and 12 months of treatment in BALB/c (± 1 mo of cortisone) and nude mice.. All rifapentine-treated mice were lung culture-negative at 3 months but 13% of BALB/c that received cortisone and 73% of nude mice relapsed. After 6, 9, and 12 months of treatment no mouse relapsed. Rifampin-treated BALB/c mice remained culture positive at 3 months. All were culture negative at 6, 9, and 12 months. None, including those receiving cortisone, relapsed. Rifampin-treated nude mice harbored more than 4 log(10) lung cfu at Month 2 and approximately 6 log(10) cfu with isoniazid resistance at Month 3. A supplementary experiment demonstrated that 7 days a week treatment did not prevent isoniazid resistance, whereas addition of ethambutol did.. In nude mice, sterilization of tuberculosis is obtained with rifapentine-containing treatment, whereas failure with development of isoniazid resistance is obtained with rifampin-containing treatment.

Topics: Animals; Anti-Inflammatory Agents; Antibiotics, Antitubercular; Antitubercular Agents; Cortisone; Disease Models, Animal; Drug Administration Schedule; Drug Resistance, Bacterial; Drug Therapy, Combination; Female; Isoniazid; Lung; Mice; Mice, Inbred BALB C; Mice, Nude; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Secondary Prevention; Time Factors; Tuberculosis, Pulmonary

The objective of this work was to evaluate the efficacy of rifampin, and its combinations with imipenem or sulbactam, in an experimental pneumonia model caused by two panresistant Acinetobacter baumannii strains (HUVR99 and HUVR113). Minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) (μg/ml) of the strains were rifampin 128/>128 for both strains, imipenem 128/>256 and 256/>256 for HUVR99 and HUVR113, respectively, and sulbactam >256/>256 for both strains. In time-kill studies, at MICs, rifampin was bactericidal for both strains and sulbactam against the HUVR99 strain. Rifampin plus imipenem or sulbactam, at the MIC or mice C (max), were synergistic. In vivo, against HUVR99 and HUVR113, rifampin (73% and 40%) and its combinations improved the survival with respect to the control group (20% and 0%, p < 0.05), respectively. Rifampin (87% and 46%) and its combinations improved the sterilization of blood cultures with respect to the control groups (0%, p < 0.05). In regard to the bacterial clearance from lungs, rifampin (2.57 ± 2.47 and 5.35 ± 3.03 log(10) cfu/g) and its combinations with imipenem or sulbactam diminished the bacterial lung concentration with respect to the control group (10.89 ± 3.00 and 11.86 ± 0.49, p < 0.05) with both strains. In conclusion, rifampin alone or associated to imipenem or sulbactam were effective for the treatment of murine pneumonia caused by selected panresistant A. baumannii strains.

Topics: Acinetobacter baumannii; Animals; Anti-Bacterial Agents; Bacterial Load; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Female; Imipenem; Lung; Mice; Mice, Inbred C57BL; Microbial Sensitivity Tests; Microbial Viability; Pneumonia, Bacterial; Rifampin; Rodent Diseases; Sulbactam; Treatment Outcome

The problems of tuberculosis (TB) and its drug resistances are very severe in China. New therapeutic agents or regimens to treat multi-drug-resistant tuberculosis (MDR-TB) are urgently needed. We studied the effects of Ag85A DNA vaccine alone or in combination with rifampin (RFP) or pyrazinamide (PZA) for the treatment of MDR-TB in mice. Ag85A DNA vaccine significantly increased the production of IFN-γ, but lowered the production of IL-4. Seventy female BALB/c mice infected with Mycobacterium tuberculosis clinical isolate HB361, which was resistant to RFP and isoniazid but sensitive to PZA, were treated with plasmid pVAX1, RFP, PZA, M. vaccae vaccine, Ag85A DNA, Ag85A DNA combined with RFP or PZA, respectively. Ag85A DNA vaccine alone or in combination with RFP or PZA reduced the pulmonary and splenic bacterial loads by 1.03-1.38 logs, respectively. Ag85A DNA combined with conventional chemotherapy for the treatment of MDR-TB might result in cure of MDR-TB in developing countries.

Topics: Acyltransferases; Animals; Antigens, Bacterial; Antitubercular Agents; Colony Count, Microbial; Combined Modality Therapy; Disease Models, Animal; Female; Interferon-gamma; Interleukin-4; Lung; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; T-Lymphocytes; Tuberculosis Vaccines; Tuberculosis, Multidrug-Resistant; Vaccines, DNA

Female BALB/cAnNCrl (n = 170; age, 6 to 9 wk) mice were infected by intravenous inoculation of 5 × 10(6) cfu Mycobacterium tuberculosis strain Erdman (ATCC 35801). Between day 52 and 5 mo after infection, 10 of the 170 mice infected according to this protocol developed torticollis, including mice in treatment groups that received combination antibiotic therapy of rifampin-pyrazinamide or moxifloxacin-rifampin-pyrazinamide. Torticollis did not develop in mice receiving isoniazid- rifampin-pyrazinamide therapy, nor was it present in the cohort of aerogenically infected mice. Affected mice were euthanized, and complete necropsy evaluation was performed on 4 mice. Gross necropsy evaluation revealed typical tuberculosis lesions in lungs of infected mice. Histologic evaluation of tissues revealed granulomatous otitis media with intralesional acid-fast bacilli consistent with Mycobacterium tuberculosis. These cases represent an unusual finding specific to the intravenous mouse model of Mycobacterium tuberculosis and may represent a model of a similar condition in humans that is known as tuberculous otitis media.

Topics: Animals; Antitubercular Agents; Autopsy; Aza Compounds; Disease Models, Animal; Drug Therapy, Combination; Ear, Middle; Female; Fluoroquinolones; Injections, Intravenous; Isoniazid; Mice; Mice, Inbred BALB C; Moxifloxacin; Mycobacterium tuberculosis; Otitis Media; Pyrazinamide; Quinolines; Rifampin; Torticollis; Tuberculosis

Central dogma suggests that rifampicin resistance in Mycobacterium tuberculosis develops solely through rpoB gene mutations.. To determine whether rifampicin induces efflux pumps activation in rifampicin resistant M. tuberculosis strains thereby defining rifampicin resistance levels and reducing ofloxacin susceptibility.. Rifampicin and/or ofloxacin minimum inhibitory concentrations (MICs) were determined in rifampicin resistant strains by culture in BACTEC 12B medium. Verapamil and reserpine were included to determine their effect on rifampicin and ofloxacin susceptibility. RT-qPCR was applied to assess expression of efflux pump/transporter genes after rifampicin exposure. To determine whether verapamil could restore susceptibility to first-line drugs, BALB/c mice were infected with a MDR-TB strain and treated with first-line drugs with/without verapamil.. Rifampicin MICs varied independently of rpoB mutation and genetic background. Addition reserpine and verapamil significantly restored rifampicin susceptibility (p = 0.0000). RT-qPCR demonstrated that rifampicin induced differential expression of efflux/transporter genes in MDR-TB isolates. Incubation of rifampicin mono-resistant strains in rifampicin (2 μg/ml) for 7 days induced ofloxacin resistance (MIC > 2 μg/ml) in strains with an rpoB531 mutation. Ofloxacin susceptibility was restored by exposure to efflux pump inhibitors. Studies in BALB/c mice showed that verapamil in combination with first-line drugs significantly reduced pulmonary CFUs after 1 and 2 months treatment (p < 0.05).. Exposure of rifampicin resistant M. tuberculosis strains to rifampicin can potentially compromise the efficacy of the second-line treatment regimens containing ofloxacin, thereby emphasising the need for rapid diagnostics to guide treatment. Efflux pump inhibitors have the potential to improve the efficacy of anti-tuberculosis drug treatment.

Topics: Adrenergic Uptake Inhibitors; Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Bacterial Proteins; Calcium Channel Blockers; Cell Culture Techniques; Disease Models, Animal; DNA-Directed RNA Polymerases; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Ofloxacin; Reserpine; Reverse Transcriptase Polymerase Chain Reaction; Rifampin; Tuberculosis, Multidrug-Resistant; Verapamil

Rifampicin has been used for the treatment of patients with jaundice and pruritus. This study evaluated the effect of rifampicin on the expression of different detoxification systems and bile acid transporters during in-vivo and in-vitro experimental models of cholestasis.. Rifampicin was administered to glycochenodeoxycholic acid (GCDCA)-treated human hepatocytes and bile duct-obstructed rats. Different parameters related to cell death, and the expression of phase I and II drug metabolizing enzymes (DME) and bile acid transporters were determined.. The induction of hepatocellular injury induced by cholestasis was associated with a reduction in cytochrome P4503A4 (CYP3A4), CYP7A1, and UDP-glucuronosyltransferase 2B4 (UGT2B4) expression, as well as an increase in import (Na(+)-taurocholate co-transporting polypeptide, NTCP) system expression. The beneficial properties of rifampicin were associated with an increase in DME and export bile acid systems (multidrug resistance-associated protein 4, MRP4, and bile acid export pump to bile duct, BSEP) expression, as well as a reduction in NTCP expression.. The beneficial effect of rifampicin in cholestasis is associated with an increase in DME expression involved in toxic, bile acid and cholesterol metabolism, as well as a reduction in the bile acid importing system in hepatocytes.

Topics: Animals; Apoptosis; Bile Acids and Salts; Carrier Proteins; Cells, Cultured; Chemical and Drug Induced Liver Injury; Cholestasis; Disease Models, Animal; Enzyme Inhibitors; Female; Gene Expression Regulation; Glycochenodeoxycholic Acid; Hepatectomy; Hepatocytes; Humans; Male; Membrane Glycoproteins; Middle Aged; Polymerase Chain Reaction; Rats; Rats, Wistar; Rifampin; RNA, Messenger

Mycobacterium tuberculosis is the causative agent of a pulmonary epidemic that is estimated to infect one-third of the world's population and that has an increased incidence of multidrug resistance. The evaluation of new chemical entities against M. tuberculosis is hampered by the lack of biological tools to help predict efficacy, from early drug development to clinical trials. As the rat is the animal species of choice in the pharmaceutical industry, we have developed a rat model of acute and chronic phases of M. tuberculosis infection for drug efficacy testing. In this model, we have evaluated the impact of tuberculosis drugs on T cell response using the enzyme-linked immunospot assay methodology. Infected rats treated with isoniazid (INH) or rifampin (RIF) responded to therapy, the potency of which was comparable to that seen in the mouse. Peripheral blood mononuclear cells from infected rats produced gamma interferon (IFN-γ) in response to RD-1 antigens, such as the 6-kDa early secretory antigen target (ESAT-6) and the 10-kDa culture filtrate protein (CFP-10). A decrease in IFN-γ spot-forming cells (SFCs) was consistently observed in response to drug treatment. In both the acute- and chronic-phase models, the T cell response was more sensitive to ESAT-6 than to CFP-10. The SFC count in response to ESAT-6 appears to be an indicator of bacterial killing in the rat. Collectively, our data suggest that the ESAT-6 response could be used as a potential surrogate of drug efficacy in the rat and that such a readout could help shorten drug testing during preclinical development.

Topics: Animals; Antibiotics, Antitubercular; Antigens, Bacterial; Antitubercular Agents; Bacterial Proteins; Disease Models, Animal; Drug Discovery; Drug Evaluation, Preclinical; Drug Resistance, Multiple, Bacterial; Enzyme-Linked Immunospot Assay; Female; Interferon-gamma; Isoniazid; Mycobacterium tuberculosis; Rats; Rats, Wistar; Rifampin; T-Lymphocytes; Tuberculosis

Multidrug-resistant and extensively drug-resistant tuberculosis (MDR/XDR-TB) is an emerging global health threat. Proper management of close contacts of infectious patients is increasingly important. However, no evidence-based recommendations for treating latent TB infection (LTBI) after MDR/XDR-TB exposure (DR-LTBI) exist. An ultrashort regimen for LTBI caused by drug-susceptible strains (DS-LTBI) is also desirable. TMC207 has bactericidal and sterilizing activity in animal models of TB and improves the activity of current MDR-TB therapy in patients.. The objective of this study was to determine whether TMC207 might enable short-course treatment of DR-LTBI and ultrashort treatment of DS-LTBI.. Using an established experimental model of LTBI chemotherapy in which mice are aerosol-immunized with a recombinant bacillus Calmette-Guérin vaccine before low-dose aerosol infection with Mycobacterium tuberculosis, the efficacy of TMC207 alone and in combination with rifapentine was compared with currently recommended control regimens as well as once-weekly rifapentine + isoniazid and daily rifapentine ± isoniazid.. Outcomes included monthly lung colony-forming unit counts and relapse rates.. Lung colony-forming unit counts were stable at about 3.75 log(10) for up to 7.5 months postinfection in untreated mice. Rifamycin-containing regimens were superior to isoniazid monotherapy. TMC207 exhibited sterilizing activity at least as strong as that of rifampin alone and similar to that of rifampin + isoniazid, but daily rifapentine +/- isoniazid was superior to TMC207. Addition of TMC207 to rifapentine did not improve the sterilizing activity of rifapentine in this model.. TMC207 has substantial sterilizing activity and may enable treatment of DR-LTBI in 3-4 months.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Diarylquinolines; Disease Models, Animal; Drug Administration Schedule; Drug Therapy, Combination; Extensively Drug-Resistant Tuberculosis; Female; Latent Tuberculosis; Lung; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Quinolines; Rifampin; Stem Cells; Treatment Outcome

Tigecycline appears as an alternative therapy against methicillin-resistant Staphylococcus aureus (MRSA) with limited clinical experience. We evaluate the efficacy of tigecycline and its combination with rifampin in comparison to that for vancomycin in a rat model of foreign-body infection by MRSA.. A tissue-cage infection model were used; therapy with tigecycline, vancomycin, rifampin, tigecycline plus rifampin and vancomycin plus rifampin was administered intraperitoneally for 7 days. The antibiotic efficacy was evaluated in the tissue-cage fluid and in the coverslips (attached bacteria); the emergence of resistance was screened.. Among monotherapies rifampin was the best treatment (decrease in log CFU/ml of tissue-cage fluid, 2.75) (P < 0.05). The addition of rifampin improved the efficacy of vancomycin (decrease, 2.28) and tigecycline (decrease, 1.56) in solitary; there were not significantly differences between tigecycline-rifampin (decrease, 3.39) and vancomycin-rifampin (decrease, 3.70), but only the latter was better than rifampin alone (P < 0.05). Resistant strains were only detected using rifampin alone.. tigecycline alone was the least effective treatment. Tigecycline-rifampin prevented the emergence of rifampin resistance, thus allowing the benefits of rifampin over time against staphylococcal foreign-body infections, but its efficacy needs to be evaluated in comparison with other anti-MRSA combined therapies.

Topics: Animals; Anti-Bacterial Agents; Diffusion Chambers, Culture; Disease Models, Animal; Drug Resistance, Bacterial; Drug Therapy, Combination; Foreign Bodies; Humans; Male; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Minocycline; Models, Animal; Rats; Rats, Wistar; Rifampin; Staphylococcal Infections; Tigecycline; Time Factors; Treatment Outcome; Vancomycin

During the syntheses and studies of natural iron chelators (mycobactins), we serendipitously discovered that a simple, small molecule, oxazoline-containing intermediate 3 displayed surprising anti-tuberculosis activity (MIC of 7.7 microM, average). Herein we report elaboration of SAR around this hit as well as the syntheses and evaluation of a hundred oxazoline- and oxazole-containing compounds derived from an efficient three step process: 1) formation of beta-hydroxy amides with serine or threonine; 2) cyclization to afford oxazolines; and 3) dehydration to give the corresponding oxazoles. A number of compounds prepared by this method were shown to possess impressive activity against Mycobacterium tuberculosis, extremely low toxicity and therefore high therapeutic indexes, as well as activity against even the more recalcitrant non-replicating form of M. tuberculosis. The uniqueness of their structures and their simplicity should allow them to be further optimized to meet ADME (absorption, distribution, metabolism, excretion) requirements. The syntheses of eight of the most potent in vitro compounds were scaled up and the compounds were tested in an in vivo mouse infection model to evaluate their efficacy before engaging upon more elaborate compound design and optimization.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Evaluation, Preclinical; Esters; Mice; Mice, Inbred BALB C; Molecular Conformation; Mycobacterium tuberculosis; Oxazoles; Stereoisomerism; Structure-Activity Relationship; Tuberculosis

Murine models of Mycobacterium tuberculosis infection are essential tools in drug discovery. Here we describe a fast standardized 9-day acute assay intended to measure the efficacy of drugs against M. tuberculosis growing in the lungs of immunocompetent mice. This assay is highly reproducible, allows good throughput, and was validated for drug lead optimization using isoniazid, rifampin, ethambutol, pyrazinamide, linezolid, and moxifloxacin.

Topics: Acetamides; Animals; Antitubercular Agents; Aza Compounds; Disease Models, Animal; Drug Discovery; Ethambutol; Fluoroquinolones; Immunocompetence; Inhalation Exposure; Isoniazid; Linezolid; Mice; Mice, Inbred C57BL; Moxifloxacin; Oxazolidinones; Pyrazinamide; Quinolines; Reproducibility of Results; Rifampin; Tuberculosis, Pulmonary

The aim of the research work was to develop and characterize rifampicin (RIF) loaded gelatin nanoparticulate delivery system for the effective management of tuberculosis. Gelatin nanoparticles (GPs) containing RIF were prepared using two-step desolvation method. Formulations were characterized through transmission electron microscopy (TEM), atomic force microscopy (AFM), size and size distribution analysis, polydispersity index (PDI), zeta potential, percent drug entrapment, percent nanoparticulate yield and in vitro drug release. Formulations were further characterized for in vitro cytotoxicity, in vivo biodistribution, and antitubercular activity. The nanoparticles were found to be spherical in shape. The size of nanoparticles was found to be 264+/-11.2 nm with low PDI suggesting the narrow particle size distribution. The drug release showed the biphasic pattern of release i.e. initial burst followed by a sustained release pattern. The cytotoxicity studies revealed that nanoparticles are safe, non toxic as compared to free drug. In vivo biodistribution study showed higher localization of RIF loaded GPs in various organs, as compared to plain RIF solution in PBS (pH 7.4). In contrast to free drug, the nanoparticles not only sustained the plasma level but also enhanced the AUC and mean residence time (MRT) of the drug, suggesting improved pharmacokinetics of drug. RIF GPs additionally resulted in significant reduction in bacterial counts in the lungs and spleen of TB-infected mice. Hence, GPs hold promising potential for increasing drug targetability vis a vis reducing dosing frequency with the interception of minimal side effects, for efficient management of tuberculosis.

Topics: Acetone; Administration, Oral; Animals; Antibiotics, Antitubercular; Area Under Curve; Cell Line; Cell Survival; Chemistry, Pharmaceutical; Delayed-Action Preparations; Disease Models, Animal; Drug Carriers; Gelatin; Injections, Intravenous; Kinetics; Macrophages; Mice; Mice, Inbred BALB C; Microscopy, Atomic Force; Microscopy, Electron, Transmission; Nanotechnology; Particle Size; Rifampin; Solubility; Surface Properties; Technology, Pharmaceutical; Tissue Distribution; Tuberculosis, Pulmonary

Norursodeoxycholic acid (norUDCA) exhibits efficient anti-cholestatic properties in an animal model of sclerosing cholangitis. norUDCA is eliminated as a C(23)-ester glucuronide (norUDCA-23G) in humans. The present study aimed at identifying the human UDP-glucuronosyltransferase (UGT) enzyme(s) involved in hepatic norUDCA glucuronidation and at evaluating the consequences of single nucleotide polymorphisms in the coding region of UGT genes on norUDCA-23G formation. The effects of norUDCA on the formation of the cholestatic lithocholic acid-glucuronide derivative and of rifampicin on hepatic norUDCA glucuronidation were also explored. In vitro glucuronidation assays were performed with microsomes from human tissues (liver and intestine) and HEK293 cells expressing human UGT enzymes and variant allozymes. UGT1A3 was identified as the major hepatic UGT enzyme catalyzing the formation of norUDCA-23G. Correlation studies using samples from a human liver bank (n = 16) indicated that the level of UGT1A3 protein is a strong determinant of in vitro norUDCA glucuronidation. Analyses of the norUDCA-conjugating activity by 11 UGT1A3 variant allozymes identified three phenotypes with high, low, and intermediate capacity. norUDCA is also identified as a competitive inhibitor for the hepatic formation of the pro-cholestatic lithocholic acid-glucuronide derivative, whereas norUDCA glucuronidation is weakly stimulated by rifampicin. This study identifies human UGT1A3 as the major enzyme for the hepatic norUDCA glucuronidation and supports that some coding polymorphisms affecting the conjugating activity of UGT1A3 in vitro may alter the pharmacokinetic properties of norUDCA in cholestasis treatment.

Topics: Animals; Cell Line; Cholangitis, Sclerosing; Cholic Acids; Disease Models, Animal; Esters; Glucuronides; Glucuronosyltransferase; Humans; Isoenzymes; Microsomes, Liver; Norsteroids; Polymorphism, Genetic; Rifampin

The present investigation deals with the evaluation of antifilarial efficacy of liposome entrapped antiwolbachial antibiotics doxycycline and rifampicin (5 doses at 10 mg/kg, subcutaneously for 15 days) alone and/or in combination with standard filaricide diethylcarbamazine (DEC) against human lymphatic filariid Brugia malayi in rodent host Mastomys coucha. The delivery system maintained the sustained release of antibiotics up to 48 h and significantly (P < 0.05) augmented the antifilarial potential of these antibiotics over their free administration. A combination of DEC with each entrapped antibiotics significantly (P<0.05) improved microfilaricidal efficacy, while marginal enhancement was noticed in adulticidal activity. Combination of both antibiotics formulation with DEC demonstrated marginal increase in macrofilaricidal efficacy; however, it was highest ( approximately 75%).

Topics: Animals; Brugia malayi; Diethylcarbamazine; Disease Models, Animal; Doxycycline; Drug Therapy, Combination; Filariasis; Filaricides; Liposomes; Male; Murinae; Rifampin

In Escherichia coli, expression of the RelE and HipA toxins in the absence of their cognate antitoxins has been associated with generating multidrug-tolerant "persisters." Here we show that unlike persisters of E. coli, persisters of Mycobacterium tuberculosis selected with one drug do not acquire cross-resistance to other classes of drugs. M. tuberculosis has three homologs of RelE arranged in operons with their apparent antitoxins. Each toxin individually arrests growth of both M. tuberculosis and E. coli, an effect that is neutralized by coexpression of the cognate antitoxin. Overexpression or deletion of each of the RelE toxins had a toxin- and drug-specific effect on the proportion of bacilli surviving antibiotic killing. All three toxins were upregulated in vivo, but none of the deletions affected survival during murine infection. RelE2 overexpression increased bacterial survival rates in the presence of rifampin in vitro, while deletion significantly decreased survival rates. Strikingly, deletion of this toxin had no discernible effect on the level of persisters seen in rifampin-treated mice. Our results suggest that, in vivo, RelE-generated persisters are unlikely to play a significant role in the generation of bacilli that survive in the face of multidrug therapy or in the generation of multidrug-resistant M. tuberculosis.

Topics: Animals; Anti-Bacterial Agents; Bacterial Proteins; Bacterial Toxins; Colony Count, Microbial; Disease Models, Animal; Drug Resistance, Bacterial; Gene Deletion; Gene Expression; Humans; Mice; Mice, Inbred C57BL; Microbial Viability; Mycobacterium tuberculosis; Rifampin; Tuberculosis

In this study, we sought to compare the sterilizing activity of human-equivalent doses of the 'Denver regimen' against acute tuberculosis (TB) infection in the standard mouse model and in the guinea pig.. Pharmacokinetic studies in guinea pigs were used to establish human-equivalent doses for rifampicin, isoniazid and pyrazinamide. Guinea pigs and mice were aerosol-infected with Mycobacterium tuberculosis CDC1551 and treatment was started 2 weeks later with rifampicin/isoniazid/pyrazinamide for up to 6 months. For the first 2 weeks of therapy, the dosing frequency was 5 days/week, and for the remaining period, twice weekly. Treatment was discontinued in groups of 30 mice and 10 guinea pigs at 5 months and at 6 months, and these animals were held for a further 3 months in order to assess relapse rates.. Guinea pig lungs became culture-negative after 3 months of predominantly twice-weekly treatment and relapse rates were 0% (0/10) both after 5 months and after 6 months of treatment. In contrast, all mice remained culture-positive despite 6 months of the same treatment, and 93% (28/30) and 69% (20/29) of mice relapsed after treatment for 5 and 6 months, respectively.. Treatment with rifampicin/isoniazid/pyrazinamide administered at human-equivalent doses is much more potent against acute TB infection in guinea pigs than in mice. Our findings have important implications for the use of alternative animal models in testing novel TB drug regimens and for modelling M. tuberculosis persistence.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Female; Guinea Pigs; Isoniazid; Lung; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Treatment Outcome; Tuberculosis

The purpose of this study was 2-fold. First, we evaluated standard chemotherapy in the guinea pig model of tuberculosis to determine if this animal species could productively be used for this purpose. Second, given the similarities of the pathology of disease in guinea pigs and humans, we wished to evaluate additional parameters, including magnetic resonance imaging, microscopy, and cytokine expression and lymphocyte phenotypes, in response to an infection treated with drug therapy. This study shows that conventional rifampin-isoniazid-pyrazinamide chemotherapy significantly decreased the numbers of the highly virulent Erdman K01 strain of Mycobacterium tuberculosis, with most of the bacilli being eliminated in a month. Despite this result, bacteria could still be detected in the lungs and other tissues for at least another 3 to 4 months. Resolution of the nonnecrotic granulomas in the lungs and lymph nodes could be clearly visualized by magnetic resonance imaging at the macroscopic level. Microscopically, the majority of the pulmonary and extrapulmonary inflammation resolved spontaneously, leaving residual lesions composed of dystrophic calcification and fibrosis marking the site of necrosis of the primary lesion. Residual calcified lesions, which were also associated with pulmonary lymphangitis, contained acid-fast bacilli even following aggressive chemotherapy. The presence of intact extracellular bacilli within these lesions suggests that these could serve as the primary sites of disease reactivation. The chemotherapy reduced the level of T-cell influx into infected tissues and was accompanied by a large and sustained increase in TH1 cytokine expression. Chemotherapy also prevented the emergence in lung tissues of high levels of interleukin-10 and Foxp3-positive cells, known markers of regulatory T cells.

Topics: Animals; Animals, Outbred Strains; Antitubercular Agents; Biomarkers; CD8-Positive T-Lymphocytes; Disease Models, Animal; Drug Therapy, Combination; Female; Flow Cytometry; Forkhead Transcription Factors; Guinea Pigs; Interleukin-10; Isoniazid; Leukocyte Common Antigens; Lung; Lymph Nodes; Magnetic Resonance Imaging; Pyrazinamide; Rifampin; Th1 Cells; Tuberculosis, Pulmonary

Topics: Amidohydrolases; Analysis of Variance; Animals; Antitubercular Agents; Colony Count, Microbial; Disease Models, Animal; Enzyme Inhibitors; Hydroxamic Acids; Isoniazid; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Rifampin; Tuberculosis

Mycobacterial persistence is thought to be the underlying cause of the current lengthy tuberculosis therapy and latent infection. Despite some recent progress, the mechanisms of bacterial persistence are poorly understood. We have recently identified a new persister gene phoU from Escherichia coli and have shown that the phoU mutant has a defect in persisters. The objective of this study is to evaluate the role of two phoU homologues phoY1 and phoY2 from Mycobacterium tuberculosis in mycobacterial persistence.. M. tuberculosis phoY1 and phoY2 mutant strains were constructed. The persister-related phenotypes of the phoY1 and phoY2 mutants were assessed in vitro by MIC testing, drug exposure assays and also by survival in the mouse model of tuberculosis infection.. We demonstrated that M. tuberculosis PhoY2 is the equivalent of E. coli PhoU in that inactivation of phoY2 but not phoY1 caused a defect in persistence phenotype as shown by increased susceptibility to rifampicin and pyrazinamide in both MIC testing and drug exposure assays and also reduced persistence in the mouse model.. This study provides further validation that PhoU is involved in persistence not only in E. coli but also in M. tuberculosis and has implications for the development of new drugs targeting persisters for improved treatment.

Topics: Animals; Antitubercular Agents; Bacterial Proteins; Colony Count, Microbial; Disease Models, Animal; Escherichia coli Proteins; Female; Gene Knockout Techniques; Lung; Membrane Transport Proteins; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Microbial Viability; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Spleen; Transcription Factors; Tuberculosis; Virulence Factors

TMC207, rifapentine, and moxifloxacin are in clinical testing for the treatment of tuberculosis. Five experimental regimens with various combinations of TMC207, rifapentine, moxifloxacin, and pyrazinamide were tested for their bactericidal and sterilizing potencies in Swiss mice intravenously inoculated with Mycobacterium tuberculosis bacilli. TMC207 had the strongest bactericidal efficacy, while rifapentine was the strongest contributor to sterilizing efficacy. The rank order of sterilizing potencies was different from the rank order of bactericidal potencies, underlining the importance of prioritizing new regimens designed to shorten the treatment duration by their sterilizing potencies rather than by their bactericidal potencies. Both 3 months of treatment with a regimen combining TMC207, pyrazinamide, and rifapentine and 5 months of treatment with a regimen combining TMC207, pyrazinamide, and moxifloxacin resulted in relapse rates similar to the rate obtained by 6 months of treatment with rifampin-isoniazid-pyrazinamide.

Topics: Animals; Antibiotics, Antitubercular; Aza Compounds; Diarylquinolines; Disease Models, Animal; Female; Fluoroquinolones; Mice; Moxifloxacin; Mycobacterium tuberculosis; Pyrazinamide; Quinolines; Rifampin; Tuberculosis

This study addressed the efficacy of daptomycin, vancomycin, rifampicin, daptomycin/rifampicin and vancomycin/rifampicin against a polysaccharide intercellular adhesin (PIA)-dependent and -independent Staphylococcus epidermidis biofilm using flow cell and guinea pig tissue cage models.. The flow cell model of both PIA-dependent and -independent biofilms demonstrated that the viable cell count after treatment with daptomycin/rifampicin was significantly lower (P<0.05) than after treatment with vancomycin, vancomycin/rifampicin, daptomycin or rifampicin alone. To validate these observations, a guinea pig tissue cage model was used. The results demonstrated that the addition of rifampicin to daptomycin or vancomycin sterilized 5/6 tissues cages colonized with S. epidermidis 1457 (PIA producing). Similar results were noted with S. epidermidis 1457 icaADBC::dhfr (non-PIA producing), where daptomycin/rifampicin and vancomycin/rifampicin sterilized 5/6 and 6/6 tissue cages, respectively. There was no statistical difference in comparison with the no-treatment control when both 1457 and 1457 icaADBC::dhfr were treated with vancomycin and daptomycin alone. Furthermore, treatment with rifampicin alone sterilized 5/6 and 3/6 1457 and 1457 icaADBC::dhfr tissue cages, respectively.. Interpretation of these data suggests that rifampicin is highly active against S. epidermidis biofilms and both vancomycin and daptomycin are effective at reducing the subpopulation of bacteria that develop rifampicin resistance.

Topics: Animals; Anti-Bacterial Agents; Biofilms; Daptomycin; Disease Models, Animal; Drug Synergism; Guinea Pigs; Microbial Sensitivity Tests; Polysaccharides, Bacterial; Rifampin; Staphylococcal Skin Infections; Staphylococcus epidermidis; Vancomycin; Virulence Factors

Post-arthroplasty infections represent a devastating complication of total joint replacement surgery, resulting in multiple reoperations, prolonged antibiotic use, extended disability and worse clinical outcomes. As the number of arthroplasties in the U.S. will exceed 3.8 million surgeries per year by 2030, the number of post-arthroplasty infections is projected to increase to over 266,000 infections annually. The treatment of these infections will exhaust healthcare resources and dramatically increase medical costs.. To evaluate novel preventative therapeutic strategies against post-arthroplasty infections, a mouse model was developed in which a bioluminescent Staphylococcus aureus strain was inoculated into a knee joint containing an orthopaedic implant and advanced in vivo imaging was used to measure the bacterial burden in real-time. Mice inoculated with 5x10(3) and 5x10(4) CFUs developed increased bacterial counts with marked swelling of the affected leg, consistent with an acute joint infection. In contrast, mice inoculated with 5x10(2) CFUs developed a low-grade infection, resembling a more chronic infection. Ex vivo bacterial counts highly correlated with in vivo bioluminescence signals and EGFP-neutrophil fluorescence of LysEGFP mice was used to measure the infection-induced inflammation. Furthermore, biofilm formation on the implants was visualized at 7 and 14 postoperative days by variable-pressure scanning electron microscopy (VP-SEM). Using this model, a minocycline/rifampin-impregnated bioresorbable polymer implant coating was effective in reducing the infection, decreasing inflammation and preventing biofilm formation.. Taken together, this mouse model may represent an alternative pre-clinical screening tool to evaluate novel in vivo therapeutic strategies before studies in larger animals and in human subjects. Furthermore, the antibiotic-polymer implant coating evaluated in this study was clinically effective, suggesting the potential for this strategy as a therapeutic intervention to combat post-arthroplasty infections.

Topics: Animals; Anti-Bacterial Agents; Arthroplasty; Disease Models, Animal; Humans; Joint Diseases; Joints; Male; Mice; Mice, Inbred C57BL; Minocycline; Postoperative Complications; Prostheses and Implants; Rifampin; Staphylococcal Infections; Staphylococcus aureus

Daptomycin exhibits rapid bactericidal activity against Gram-positive organisms, including meticillin-resistant Staphylococcus aureus (MRSA). Daptomycin in combination with rifampicin needs to be assessed in bone infection. An MRSA acute osteomyelitis model was used. Daptomycin and vancomycin were compared, alone or in combination with rifampicin, over 4 days. Surviving bacteria were counted in bone, bone marrow and joint fluid. Vancomycin and daptomycin as single therapies were ineffective, but both combinations were significantly more effective than the corresponding monotherapy. Combination of daptomycin and rifampicin could prevent S. aureus from developing resistance. This combination could be a useful alternative to treat MRSA osteomyelitis at an early stage.

Topics: Animals; Anti-Bacterial Agents; Bacterial Load; Bone and Bones; Bone Marrow; Daptomycin; Disease Models, Animal; Drug Therapy, Combination; Female; Joints; Methicillin-Resistant Staphylococcus aureus; Osteomyelitis; Rabbits; Rifampin; Staphylococcal Infections; Treatment Outcome; Vancomycin

To investigate the efficacy of daptomycin and rifampin either alone or in combination in preventing prosthesis biofilm in a rat model of staphylococcal vascular graft infection.. Prospective, randomised, controlled animal study.. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses followed by topical inoculation with 2×10(7) colony forming units of Staphylococcus aureus, strain Smith diffuse.. The study included a control group, a contaminated group that did not receive any antibiotic prophylaxis and three contaminated groups that received intra-peritoneal daptomycin, rifampin-soaked graft and daptomycin plus rifampin-soaked graft, respectively. Each group included 15 animals. The infection burden was evaluated by using sonication and quantitative agar culture. Moreover, an in vitro antibiotic susceptibility assay for S. aureus biofilms was performed to elucidate the same activity.. When tested alone, daptomycin and rifampin showed good efficacies. Their combination showed efficacies significantly higher than that of each single compound. The in vitro studies showed that minimum inhibitory concentration and minimum bactericidal concentration values for daptomycin were lower in presence of rifampin. Daptomycin prevented the emergence of rifampin resistance.. Daptomycin is an important candidate for prevention of staphylococcal biofilm-related infection and rifampin could serve as an interesting anti-staphylococcal antibiotic enhancer.

Topics: Animals; Anti-Bacterial Agents; Antibiotic Prophylaxis; Biofilms; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Coated Materials, Biocompatible; Colony Count, Microbial; Daptomycin; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Male; Microbial Sensitivity Tests; Polyethylene Terephthalates; Prospective Studies; Prosthesis Design; Prosthesis-Related Infections; Random Allocation; Rats; Rats, Wistar; Rifampin; Staphylococcal Infections; Staphylococcus aureus

Device-related infections represent a significant clinical challenge. Once established, these infections prove difficult to treat with existing antibiotic regimens, compromising the health of device recipients, and usually requiring surgical intervention to resolve. The purpose of this study was to determine the ability of the AIGIS(RX)® Anti-Bacterial envelope to reduce the formation of bacterial biofilm on implanted pacing devices.. An infection was established in a rabbit model by creating bilateral subcutaneous implant pockets, into which a pacing device with or without AIGIS(RX)® was placed. The incisions were closed, and a defined dose of bacteria was infused into each implant pocket. After seven days, devices were explanted and assessed for viable bacteria by a sonication/vortex procedure to quantify bacteria, and by imaging of the device surface by scanning electron microscopy and laser scanning confocal microscopy.. The presence of the AIGIS(RX)® envelope eliminated recoverable, viable bacteria from the explanted devices using a vortex/sonication technique from in vivo models of Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus capitis, and Escherichia coli infections. Scanning electron microscopy and confocal microscopy demonstrate greatly reduced biological material on the pacemaker surfaces in the presence of the AIGIS(RX)® envelope compared to untreated controls.. These results demonstrate that in this animal model, the AIGIS(RX)® device reduces the formation of adherent bacteria and reduces bioburden on implanted, infected pacemaker devices.

Topics: Animals; Anti-Bacterial Agents; Bacterial Adhesion; Biofilms; Disease Models, Animal; Drug Therapy, Combination; Equipment Contamination; Escherichia coli; Escherichia coli Infections; Microbial Viability; Microscopy, Confocal; Microscopy, Electron, Scanning; Minocycline; Pacemaker, Artificial; Rabbits; Rifampin; Staphylococcal Infections; Staphylococcus; Time Factors

To investigate the effects and possible mechanism of rifampicin on steroid-induced osteonecrosis of the femoral head (ONFH).. Bone marrow stromal cells (BMSC) separated from male rats were cultured in vitro without any treatment (Group mA), exposed to dexamethasone (Group mB), treated with rifampicin (Group mC), and exposed to dexamethasone and rifampicin simultaneously (Group mD) respectively (n = 5 in each group). After 7 days, P-glycoprotein (P-gp) activity and adipogenesis of the BMSC were evaluated. In an in vivo experiment, 80 rats were randomly divided into 4 groups (n= 20 in each group). Group A received intragastric saline for 5 weeks. Group B received intragastric saline for one week, followed by subcutaneous methylprednisolone and saline for 4 weeks. Group C received intragastric rifampicin for 5 weeks. Group D received intragastric rifampicin for one week, followed by subcutaneous methylprednisolone and rifampicin for 4 weeks. At the end of the experiment, all rats underwent analysis of P-gp activity of BMSC, P-gp expression in the femoral heads, MRI and histomorphometry of the femoral heads.. In vitro, the P-gp activity of BMSC increased and lipid accumulation decreased significantly in Group mD, compared to Group mB. In vivo, P-gp activity and P-gp expression in Group D increased compared to Group B. The mean area of MRI abnormal signal, adipocytic variables and apoptotic cells in Group D decreased, mean percentage of the whole epiphysis made up by the epiphyseal ossification center and trabecular structure variables improved compared to those in Group B. The incidence of ONFH was lower in Group D (50%) than in Group B (80%).. Rifampicin may decrease the risk of steroid-induced ONFH by enhancing P-gp activity, thus preventing steroid-induced BMSC adipogenesis.

Topics: Adipogenesis; Animals; ATP Binding Cassette Transporter, Subfamily B, Member 1; Bone Marrow Cells; Cells, Cultured; Dexamethasone; Disease Models, Animal; Drug Evaluation, Preclinical; Femur Head; Femur Head Necrosis; Glucocorticoids; Magnetic Resonance Imaging; Male; Methylprednisolone; Rats; Rats, Sprague-Dawley; Rifampin; Risk; Stromal Cells

Acinetobacter baumannii is an important cause of nosocomial infection with increasing carbapenem resistance. The aim of this study was to compare the efficacy of colistin+rifampicin and imipenem+rifampicin combinations with that of several other antibiotic regimens against carbapenem-resistant A. baumannii pneumonia using an immunosuppressed mouse model. Three different A. baumannii strains with diverse resistance mechanisms (OXA-51-, IMP-1- and VIM-2-type beta-lactamases) were used. Among the monotherapy regimens, only rifampicin significantly reduced the bacterial load in lungs 24 h after infection with the OXA-51-producing strain. Addition of rifampicin to either imipenem or colistin yielded synergistic results after 48 h. Rifampicin was bactericidal against the IMP-1-producing strain, and only the imipenem+rifampicin combination yielded synergistic effects. In contrast, rifampicin alone was not effective against the VIM-2-producing strain, but the imipenem+rifampicin combination was bacteriostatic even at 24 h post-infection. Tigecycline and amikacin were not effective against any of the three strains. Rifampicin-based combinations were effective against A. baumannii bacteraemia and improved survival regardless of the strain type. Contrary to the similar minimum inhibitory concentration results, the antibacterial effects of rifampicin were quite different according to the strains; a tailored antibiotic strategy must be considered in treatment. Addition of rifampicin to either imipenem or colistin would be effective.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Carbapenems; Colistin; Disease Models, Animal; Drug Resistance, Bacterial; Drug Therapy, Combination; Female; Humans; Imipenem; Immunosuppression Therapy; Mice; Mice, Inbred ICR; Microbial Sensitivity Tests; Neutropenia; Pneumonia, Bacterial; Rifampin; Treatment Outcome

R207910 (TMC207 or J) is a member of the diarylquinolines, a new family of antituberculous drugs with high bactericidal activity when given daily in the murine model of tuberculosis. R207910 exhibits a long half-life and thus is a good candidate for once-weekly therapy of tuberculosis.. To study the activity of once-weekly R207910 monotherapy and combinations of R207910 with other antituberculous agents (isoniazid, rifapentine, moxifloxacin, and pyrazinamide).. The established infection model of murine tuberculosis was used. Colony counts were determined in the lungs.. Eight weeks of monotherapy reduced the bacillary load by 3 to 4 log(10) for rifapentine and by 5 to 6 log(10) for R207910 (P < 0.05). The addition of rifapentine and isoniazid or moxifloxacin did not improve the bactericidal activity of R207910 monotherapy. In contrast, the triple combination of R207910 plus rifapentine plus pyrazinamide given once weekly for 2 months (i.e., a total of only eight administrations), was significantly (P < 0.05) more active than R207910 monotherapy or other R207910 combinations, and led to lung culture negativity in 9 of 10 mice, whereas all lungs were culture positive in the groups treated with other drug combinations. Moreover, R207910 plus rifapentine plus pyrazinamide given once weekly was more active than the current standard regimen of rifampin plus isoniazid plus pyrazinamide given five times per week.. The unprecedented activity of the triple combination of R207910 plus rifapentine plus pyrazinamide suggests that it may be feasible to develop a fully intermittent once-weekly regimen.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Colony Count, Microbial; Diarylquinolines; Disease Models, Animal; Drug Therapy, Combination; Female; Lung; Mice; Pyrazinamide; Quinolines; Rifampin; Tuberculosis

Meropenem is a broad-spectrum carbapenem antibiotic that is highly active against the pathogens causing meningitis. The aims of this study was to determine the efficacies of meropenem alone and combined with rifampin against two Streptococcus pneumoniae strains with different susceptibility to beta-lactams using the guinea pig meningitis model and compare them with the standard ceftriaxone plus vancomycin therapy. All treatments except rifampin were bactericidal from 6 h. The addition of rifampin did not improve the activity of meropenem alone. Our results provide good evidence of the efficacy of meropenem in the treatment of penicillin- and cephalosporin-susceptible and -resistant pneumococcal meningitis similar to that of ceftriaxone plus vancomycin, suggesting that meropenem might be a good option in the management of this infection.

Topics: Animals; Anti-Bacterial Agents; Ceftriaxone; Colony Count, Microbial; Disease Models, Animal; Drug Therapy, Combination; Female; Guinea Pigs; Humans; Meningitis, Pneumococcal; Meropenem; Microbial Viability; Rifampin; Streptococcus pneumoniae; Thienamycins; Time Factors; Treatment Outcome; Vancomycin

The combination of levofloxacin and rifampin has been recommended for the treatment of staphylococcal prosthetic infection. In a rabbit model of prosthetic knee infection due to a susceptible clinical strain of Staphylococcus aureus, the combination of levofloxacin and rifampin was bactericidal, significantly reduced bacterial titers in bone compared with levels for rifampin and controls (P < 0.05), sterilized 6 of 12 animals, and prevented the selection of resistant mutants that was observed with rifampin alone, validating clinical recommendations.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Therapy, Combination; Humans; Knee Prosthesis; Levofloxacin; Methicillin; Microbial Sensitivity Tests; Ofloxacin; Prosthesis-Related Infections; Rabbits; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Treatment Outcome

To investigate the efficacy of buforin II and rifampin in an experimental rat model of Acinetobacter baumannii sepsis.. Prospective, randomized, controlled animal study.. Research laboratory in a university hospital.. Adult male Wistar rats.. The animals received intraperitoneally 1 mL saline containing 2 x 10 colony forming units of A. baumannii ATCC 19606 (model i) or the multiresistant strain (model ii). Immediately after bacterial challenge, animals received intravenously a single dose of isotonic sodium chloride solution (control groups C1 and C2), 1 mg/kg of buforin II, 10 mg/kg of rifampin, and 1 mg/kg of buforin II plus 10 mg/kg of rifampin, respectively.. Lethality, bacterial growth in blood and tissue burden, endotoxin, interleukin-6, and tumor necrosis factor-alpha concentrations in plasma. Buforin II showed good antimicrobial activity and achieved a significant reduction of plasma endotoxin and cytokines concentration when compared with control and rifampin-treated groups. Combination among buforin II proved to be the most effective treatment in reducing all variables measured.. In an experimental model, buforin II and rifampin might have a potential role in the treatment of severe infections due to A. baumannii.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Antibiotics, Antitubercular; Disease Models, Animal; Male; Proteins; Rats; Rats, Wistar; Rifampin; Sepsis

Synthetic vascular conduits used in traumatic or infected fields have a high failure rate leading to catastrophic consequences including amputation and death. Although efforts to coat vascular grafts with antibiotics have had varying results, we developed a novel coating technique for expanded-polytetrafluoroethylene (ePTFE), which has proven to be effective in vitro. Thus, we hypothesized that the coated grafts would resist infection and have decreased neointimal hyperplasia when used in vivo in a large animal model.. Minocycline and rifampin suspended in a mixture of methacrylates were coated onto a 3cm segment of 6mm ePTFE (Bard, Tempe, AZ). An antibiotic-coated (ABX), adhesive-coated (AC), or control (C) ePTFE graft was then placed as an end-to-side graft into the left iliac artery of a male mongrel pig. Sterile saline or innoculum containing 3x10(8)Staphylococcus aureus (SA) or Staphylococcus epidermidis (SE) was then placed directly on the graft and the reflected peritoneum re-approximated to confine the bacteria. After 6 wk, the graft was harvested, cultured, and morphometric analyses of neointimal hyperplasia were performed.. Twenty-seven pigs had grafts placed (9 ABX, 9 AC, 9 C) and harvested. Of the nine grafts exposed to SA, the uncoated and adhesive-coated grafts averaged greater than 50,000 colonies of SA while the antibiotic-coated grafts averaged less than 50 colonies. Although not statistically significant, neointimal hyperplasia was decreased by 15% to 20% when using an ABX graft in an infected field.. The coated grafts appeared to decrease NIH formation although not significantly in this small pilot study. The methacrylate antibiotic-coated ePTFE graft did provide resistance to infection when used in infected fields.

Topics: Adhesives; Animals; Anti-Bacterial Agents; Blood Vessel Prosthesis; Coated Materials, Biocompatible; Disease Models, Animal; Hyperplasia; Male; Methacrylates; Microscopy, Electron, Scanning; Minocycline; Pilot Projects; Polytetrafluoroethylene; Prosthesis-Related Infections; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Staphylococcus epidermidis; Swine

In bacterial meningitis, severe systemic and local inflammation causes long-term impairment and death of affected patients. The current antibiotic therapy relies on cell wall-active beta-lactam antibiotics, which rapidly sterilize the cerebrospinal fluid (CSF). However, beta-lactams inhibit cell wall synthesis, induce bacteriolysis, and thereby evoke a sudden release of high amounts of toxic and proinflammatory bacterial products. Because tissue damage in bacterial meningitis is the result of bacterial toxins and the inflammatory host response, any reduction of free bacterial compounds promises to prevent neuronal damage.. In vitro experiments and randomized prospective animal study.. University research laboratories.. Streptococcus pneumoniae broth cultures and New Zealand White rabbits.. We evaluated a concept to improve bacterial meningitis therapy in which a short-term pretreatment with the protein synthesis-inhibiting antibiotic rifampicin precedes the standard antibiotic therapy with ceftriaxone. First, logarithmically growing pneumococcal cultures were subdivided and exposed to different antibiotics. Then, rabbits suffering from pneumococcal meningitis were randomized to receive rifampicin pretreatment or ceftriaxone alone.. In pneumococcal cultures, quantitative immunoblotting and real-time polymerase chain reaction revealed a reduced release of pneumolysin and bacterial DNA by rifampicin pretreatment for 30 minutes in comparison with ceftriaxone treatment alone. In vivo, a 1-hour rifampicin pretreatment reduced the release of bacterial products and attenuated the inflammatory host response, as demonstrated by decreased CSF levels of prostaglandin E2 and total protein and increased glucose CSF/plasma ratios. Rifampicin pretreatment reduced infection-associated neuronal apoptotic cell loss compared with ceftriaxone-treated controls.. A short-term pretreatment with rifampicin reduced the beta-lactam-induced release of deleterious bacterial products, attenuated inflammation, and thereby decreased neuronal cell loss in experimental bacterial meningitis. This concept has the potential to reduce inflammation-associated neuronal injury in bacterial meningitis and should be evaluated in a clinical trial.

Topics: Animals; Anti-Bacterial Agents; Apoptosis; Ceftriaxone; Cell Culture Techniques; Disease Models, Animal; Drug Administration Schedule; Drug Therapy, Combination; Meningitis, Pneumococcal; Neurons; Rabbits; Rifampin

The diarylquinoline R207910 (TMC207) has potent bactericidal activity in a murine model of tuberculosis (TB), but its sterilizing activity has not been determined.. To evaluate the sterilizing activity of R207910-containing combinations in the murine model of TB.. Swiss mice were intravenously inoculated with 6 log(10) of Mycobacterium tuberculosis strain H37Rv, treated with R207910-containing regimens, and followed for 3 months to determine relapse rates (modified Cornell model).. Quantitative lung and spleen colony-forming unit counts and bacteriological relapse rates 3 months after the end of therapy were compared for the following regimens: 2, 3, or 4 months of R207910 (J) and pyrazinamide (Z) combined with rifampin (R) or isoniazid (H) or both and 3 or 4 months of a moxifloxacin (M)-containing regimen and 6 months of the standard WHO regimen RHZ. All J-treated mice were culture negative after 4 months of therapy. The relapse rate in the group treated with 4 months of JHRZ was similar to that of mice treated for 6 months with the RHZ regimen (6 vs. 17%; P = 0.54) and lower than that of RMZ (6 vs. 42%; P = 0,03), a moxifloxacin-containing regimen that was the most active in mice on once-daily basis.. Four months of treatment with some J-containing regimens was as effective as the 6-month standard regimen and more effective than 4 months of treatment with M-containing regimens. Supplementation of standard regimen (RHZ) with J or substitution of J for H may shorten the treatment duration needed to cure TB in patients.

Topics: Animals; Antitubercular Agents; Diarylquinolines; Disease Models, Animal; Drug Therapy, Combination; Female; Hydrolases; Isoniazid; Mice; Mycobacterium tuberculosis; Pyrazinamide; Quinolines; Rifampin; Tuberculosis; Tuberculosis, Pulmonary; Tuberculosis, Splenic

Monitoring the spread of mycobacterium in vivo using biophotonic imaging provides a fast, reliable and sensitive method to evaluate the distribution of the infection. Moreover, this technique allows for a significant reduction in the number of animals required in comparison to conventional anatomopathological studies. Here, we describe for the first time and validate the use of a luciferase-tagged recombinant Mycobacterium bovis BCG for non-invasive bioluminescent imaging of 1) bacterial dissemination in tissues, 2) the efficacy of treatment with anti-mycobacterial drugs and 3) the role of adaptive immune responses in controlling mycobacterial infection in vivo.

Topics: Animals; Antitubercular Agents; Diagnostic Imaging; Disease Models, Animal; Humans; Isoniazid; Luciferases; Luminescent Measurements; Mice; Mycobacterium bovis; Rifampin; Treatment Outcome; Tuberculosis

Regimens recommended to treat latent tuberculosis infection (LTBI) are 3 to 9 months long. A 2-month rifampin+pyrazinamide regimen is no longer recommended. Shorter regimens are highly desirable. Because substituting rifapentine for rifampin in the standard regimen for active tuberculosis halves the treatment duration needed to prevent relapse in mice, we hypothesized daily rifapentine-based regimens could shorten LTBI treatment to 2 months or less.. To improve an existing model of LTBI chemotherapy and evaluate the efficacy of daily rifapentine-based regimens.. Mice were immunized with a more immunogenic recombinant Bacille Calmette-Guérin strain (rBCG30) and received very low-dose aerosol infection with Mycobacterium tuberculosis to establish a stable lung bacterial burden below 10(4) CFU without drug treatment. Mice received a control (isoniazid alone, rifampin alone, rifampin+isoniazid, rifampin+pyrazinamide) or test (rifapentine alone, rifapentine+isoniazid, rifapentine+pyrazinamide, rifapentine+isoniazid+pyrazinamide) regimen for 8 weeks. Rifamycin doses were 10 mg/kg/d, analogous to the same human doses. Outcomes were biweekly lung CFU counts and relapse after 4 to 8 weeks of treatment.. M. tuberculosis CFU counts remained stable around 3.65 log(10) in immunized, untreated mice. Isoniazid or rifampin left all or most mice culture-positive at week 8. Rifampin+isoniazid cured 0 and 53% of mice and rifampin+pyrazinamide cured 47 and 100% of mice in 4 and 8 weeks, respectively. Rifapentine-based regimens were more active than rifampin+isoniazid and indistinguishable from rifampin+pyrazinamide.. In this improved murine model of LTBI chemotherapy with very low lung burden, existing regimens were well represented. Daily rifapentine-based regimens were at least as active as rifampin+pyrazinamide, suggesting they could effectively treat LTBI in 6 to 8 weeks.

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Drug Administration Schedule; Female; Lung; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Rifampin; Treatment Outcome; Tuberculosis

To develop an animal model of intraocular tuberculosis (TB) with features of pulmonary TB and extrapulmonary dissemination to the eye.. Hartley strain guinea pigs were infected via an aerosol route with virulent Mycobacterium tuberculosis. One group of guinea pigs was infected with a relatively low bacterial inoculum and received no treatment. A second group of guinea pigs received high-dose infection and were treated with the first-line anti-TB drugs isoniazid, rifampin, and pyrazinamide. Development of ocular TB lesions was documented by histological analysis, acid-fast staining, and real-time polymerase chain reaction for M tuberculosis DNA.. Untreated guinea pigs developed pulmonary and extrapulmonary TB. Ocular TB, primarily involving the uvea, developed in 5 of 12 eyes (42%). Uveal granulomatous lesions showed the presence of acid-fast organisms and M tuberculosis DNA. In treated animals, none of the 8 eyes examined revealed the presence of acid-fast organisms; however, there was mild nongranulomatous uveitis in 4 eyes.. Mycobacterium tuberculosis delivered via aerosol to guinea pigs results in extrapulmonary dissemination to the eye. Of significance, intraocular changes in this model include granulomatous inflammation and the presence of acid-fast organisms, as seen in human cases of ocular TB. Clinical Relevance The guinea pig model may provide greater insight into the pathogenesis of intraocular TB and assist in the development of novel modalities to treat this global infectious disease.

Topics: Aerosols; Animals; Antitubercular Agents; Disease Models, Animal; DNA, Bacterial; Guinea Pigs; Isoniazid; Lung; Mycobacterium tuberculosis; Polymerase Chain Reaction; Pyrazinamide; Rifampin; Spleen; Tuberculosis, Ocular; Tuberculosis, Pulmonary

Screening of new agents for anti-tubercular activity is a challenging task due to the virulent and slow growing nature of mycobacteria. In this study, we explored the use of Mycobacterium smegmatis as an alternate model to virulent strains. We observed that the effect of standard anti-tubercular drugs was similar in mice infected with M. smegmatis and Mycobacterium tuberculosis. The total duration of the experiment, including incubation time, was 10 days in the M. smegmatis-infected mice model compared with 2 months in M. tuberculosis-infected mice. This model of anti-tubercular screening is a simple, easy to carry out, less time-consuming, safer and economical alternative for preliminary in vivo screening of potential anti-tubercular agents.

Topics: Animals; Antitubercular Agents; Colony Count, Microbial; Disease Models, Animal; Drug Discovery; Female; Fluoroquinolones; Gatifloxacin; Isoniazid; Lung; Male; Mice; Mycobacterium Infections; Mycobacterium smegmatis; Mycobacterium tuberculosis; Rifampin; Spleen

The inhaled form of Bacillus anthracis infection may be fatal to humans. The current standard of care for inhalational anthrax postexposure prophylaxis is ciprofloxacin therapy twice daily for 60 days. The potent in vitro activity of oritavancin, a semisynthetic lipoglycopeptide, against B. anthracis (MIC against Ames strain, 0.015 microg/ml) prompted us to test its efficacy in a mouse aerosol-anthrax model. In postexposure prophylaxis dose-ranging studies, a single intravenous (i.v.) dose of oritavancin of 5, 15, or 50 mg/kg 24 h after a challenge with 50 to 75 times the median lethal dose of Ames strain spores provided 40, 70, and 100% proportional survival, respectively, at 30 days postchallenge. Untreated animals died within 4 days of challenge, whereas 90% of control animals receiving ciprofloxacin at 30 mg/kg intraperitoneally twice daily for 14 days starting 24 h after challenge survived. Oritavancin demonstrated significant activity post symptom development; a single i.v. dose of 50 mg/kg administered 42 h after challenge provided 56% proportional survival at 30 days. In a preexposure prophylaxis study, a single i.v. oritavancin dose of 50 mg/kg administered 1, 7, 14, or 28 days before lethal challenge protected 90, 100, 100, and 20% of mice at 30 days; mice treated with ciprofloxacin 24 h or 24 and 12 h before challenge all died within 5 days. Efficacy in pre- and postexposure models of inhalation anthrax, together with a demonstrated low propensity to engender resistance, promotes further study of oritavancin pharmacokinetics and efficacy in nonhuman primate models.

Topics: Administration, Inhalation; Animals; Anthrax; Anti-Bacterial Agents; Bacillus anthracis; Disease Models, Animal; Glycopeptides; Humans; Lipoglycopeptides; Mice; Microbial Sensitivity Tests; Spores, Bacterial; Treatment Outcome

To investigate the effects of rifampicin in a mouse model of endotoxin shock, mice were pretreated with rifampicin for at different times before and after challenging with a lethal dose of lipopolysaccharide (LPS). We found that rifampicin had a significant preventive effect and reduced the mortality of mice at early stages. To further understand the mechanism, plasma cytokine levels were examined. Mice treated with LPS alone showed markedly increased plasma levels of TNF, IL-1beta, IL-6, and IL-10, while mice pretreated with rifampicin showed significantly lower plasma levels of these cytokines compared to the LPS alone. Our results suggest that rifampicin has a beneficial effect on septic shock caused by LPS through modulation of cytokines. This suggests that rifampicin could be a candidate for treatment of septicemia caused by gram-negative bacterial infection.

Topics: Animals; Anti-Bacterial Agents; Cytokines; Disease Models, Animal; Drug Administration Schedule; Female; Inflammation Mediators; Interleukin-10; Interleukin-1beta; Interleukin-6; Lipopolysaccharides; Mice; Mice, Inbred C57BL; Rifampin; Shock, Septic; Time Factors; Tumor Necrosis Factor-alpha

New drugs are needed to shorten the duration of tuberculosis treatment. R207910, a diarylquinoline, is very active against Mycobacterium tuberculosis both in vitro and in mice. In healthy volunteers, the coadministration of R207910 and rifampin induced the increased metabolism of R207910, resulting in a 50% reduction in the level of R207910 exposure. We assessed the impact of reducing the dose of R207910 on its efficacy when R207910 was combined with a background regimen of isoniazid, rifampin, and pyrazinamide. Addition of 25 mg/kg of body weight or 12.5 mg/kg R207910 to the background regimen resulted in faster bacterial clearance and culture negativity. The difference in efficacy between the two doses was not statistically significant. The minimal bactericidal dose of R207910 when it was tested as part of the combination was identical to that when it was tested as monotherapy. Because of the drug-drug interaction in humans, the activity of R207910 in humans could be less than that expected from studies with mice. Our data from the mouse model demonstrate that R207910 has significant activity, even when its exposure is reduced by 50% and when it is added to a strong background regimen of isoniazid, rifampin, and pyrazinamide. In killing kinetic studies, the bactericidal effect of R207910 in mice was modest during the first week of treatment, but it increased in the following 3 weeks, while the bactericidal activity of isoniazid was limited to the first week of treatment.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Colony Count, Microbial; Diarylquinolines; Disease Models, Animal; Drug Interactions; Female; Humans; Isoniazid; Lung; Mice; Mycobacterium tuberculosis; Pyrazinamide; Quinolines; Rifampin; Spleen; Tuberculosis, Pulmonary

PA-824 is in phase II clinical testing to treat tuberculosis. At a dose of 100 mg/kg of body weight, it has demonstrated bactericidal activity during the initial and continuation phases of treatment in a murine model of tuberculosis. In a prior study, substitution of PA-824 for isoniazid in the first-line regimen of rifampin, isoniazid, and pyrazinamide resulted in significantly lower CFU counts at 2 months and shorter time to culture-negative conversion. However, the study design prevented a rigorous assessment of the relapse rate after completion of therapy. The current experiment was designed to assess (i) the extent of the beneficial effect of substituting PA-824 for isoniazid in the first-line regimen, (ii) the influence of the PA-824 dose on the same effect, and (iii) the activity of each one-, two-, and three-drug combination of rifampin, PA-824, and pyrazinamide. Mice were infected by the aerosol route and initiated on treatment 14 days later with more than 7 log(10) CFU per lung. Treatment with rifampin and pyrazinamide was more effective than treatment with rifampin, isoniazid, and pyrazinamide at reducing the lung CFU count, consistent with past evidence of isoniazid's antagonism in this model. The addition of PA-824 at 12.5 and 25 mg/kg/day did not increase the activity of rifampin plus pyrazinamide, but the addition of PA-824 at 50 and 100 mg/kg/day did increase the activity in a dose-dependent manner. The combination of rifampin, PA-824 (100 mg/kg), and pyrazinamide rendered all mice culture negative after 2 months of treatment and free of relapse after 4 months of treatment, while some mice receiving rifampin, isoniazid, and pyrazinamide remained culture positive and 15% relapsed after completing 4 months of treatment. The two-drug combination of PA-824 and pyrazinamide displayed synergistic activity that was equivalent to that of the standard first-line regimen. Together, these results support the evaluation of regimens based on the combination of rifampin, PA-824, and pyrazinamide in phase II clinical trials while demonstrating several potential pitfalls in the evaluation of new drug combinations in a murine model of tuberculosis.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Colony Count, Microbial; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Female; Isoniazid; Lung; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Nitroimidazoles; Pyrazinamide; Recurrence; Rifampin; Tuberculosis, Pulmonary

Multiple system atrophy (MSA) is a progressive neurodegenerative disorder characterized by oligodendrocytic cytoplasmic inclusions containing abnormally aggregated alpha-synuclein. This aggregation has been linked to the neurodegeneration observed in MSA. Current MSA treatments are aimed at controlling symptoms rather than tackling the underlying cause of neurodegeneration. This study investigates the ability of the antibiotic rifampicin to reduce alpha-synuclein aggregation and the associated neurodegeneration in a transgenic mouse model of MSA. We report a reduction in monomeric and oligomeric alpha-synuclein and a reduction in phosphorylated alpha-synuclein (S129) upon rifampicin treatment. This reduction in alpha-synuclein aggregation was accompanied by reduced neurodegeneration. On the basis of its anti-aggregenic properties, we conclude that rifampicin may have therapeutic potential for MSA.

Topics: alpha-Synuclein; Animals; Antibiotics, Antitubercular; beta-Synuclein; Blotting, Western; Disease Models, Animal; Humans; Immunohistochemistry; Inclusion Bodies; Injections, Intraperitoneal; Mice; Mice, Transgenic; Microscopy, Confocal; Multiple System Atrophy; Nerve Degeneration; Oligodendroglia; Rifampin; Synucleins

Recent studies have demonstrated that combined substitutions of rifapentine for rifampin and moxifloxacin for isoniazid in the standard, daily, short-course regimen of rifampin, isoniazid, and pyrazinamide produces stable cure in 12 weeks or less. This study was designed to more precisely evaluate the contribution of moxifloxacin and isoniazid to rifapentine-based regimens.. We compared bactericidal activity and treatment-shortening potential between regimens consisting of isoniazid or moxifloxacin plus rifapentine and pyrazinamide administered either thrice-weekly or daily.. Using a mouse model of tuberculosis, we assessed bactericidal activity by performing quantitative cultures of lung homogenates over the first 12 weeks of treatment. Relapse rates were assessed after completing 8, 10, and 12 weeks of treatment to determine the duration of treatment necessary for stable cure.. After 4 weeks of treatment, daily and thrice-weekly therapy with rifapentine, moxifloxacin, and pyrazinamide was significantly more active than treatment with rifapentine, isoniazid, and pyrazinamide. By 8 weeks of treatment, all mice receiving the moxifloxacin-containing regimens were lung culture negative, whereas those mice receiving the isoniazid-containing regimens continued to be lung culture positive. However, the duration of treatment necessary to achieve stable cure was 10 weeks for daily regimens and 12 weeks for thrice-weekly regimens, regardless of whether isoniazid or moxifloxacin was used. All mice receiving standard daily therapy with rifampin, isoniazid, and pyrazinamide relapsed after 12 weeks of treatment.. These results suggest that regimens consisting of isoniazid or moxifloxacin plus rifapentine and pyrazinamide may dramatically shorten the duration of treatment needed to cure human tuberculosis.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Aza Compounds; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Fluoroquinolones; Isoniazid; Lung; Mice; Mice, Inbred BALB C; Moxifloxacin; Pyrazinamide; Quinolines; Recurrence; Rifampin; Time Factors; Treatment Outcome; Tuberculosis

The primary objective of this study was to compare the efficacy of a collagen silver-coated polyester graft, InterGard, with a gelatin-sealed graft, Gelsoft, both soaked in rifampin, for resistance to direct bacterial contamination in an animal model. The second objective was to confirm the lack of inflammation from silver acetate. Vascular grafts, 6 mm in diameter, were implanted in the infrarenal aorta of 28 dogs. Intravenous cefamandole (20 mg/kg) was injected intraoperatively in all dogs. The dogs were divided into three groups. Group I included 12 dogs. Six dogs received silver grafts and six dogs received gelatin-sealed grafts, all soaked with rifampin. Grafts implanted in group I were directly infected with methicillin-resistant Staphylococcus aureus (MRSA). Group II included also six silver grafts and six gelatin-sealed grafts, all soaked with rifampin. Dogs of group II were directly infected with Escherichia coli. Group III comprised four dogs, which received gelatin unsealed grafts, directly infected with MRSA, the control group. All dogs were followed by regular clinical examination, including blood cultures. Grafts in groups I and III and in group II were harvested at 30 days and 10 days, respectively. Bacterial analyses were performed on the explanted grafts. Histology was performed on both the tissue samples and the anastomotic sites of the harvested grafts. In group I, no grafts were infected with MRSA, irrespective of graft type. In group II, no silver grafts were infected with E. coli, whereas one (16.6%) of six gelatin-sealed grafts was infected (p = 0.317). In group III, three (75%) of the four grafts were infected with MRSA. The infection rate in the silver grafts and the gelatin-sealed grafts soaked in rifampin in group I compared with the unsealed gelatin grafts in group III was statistically significantly different (p < 0.05). There was no statistically significant difference in the inflammation score, obtained by histological analysis, between rifampin-soaked silver and Gelsoft grafts in either group I or group II. There were signs of necrosis at the anastomoses in three (25%) gelsoft grafts of 12 in groups I and II. There were no clinical or biological signs of inflammation from use of silver-coated grafts. These results indicate that collagen silver-coated grafts and gelatin-sealed grafts, both soaked in rifampin, provide resistance against MRSA and E. coli. There was a trend toward better resistance but without statistical signi

Topics: Acetates; Animals; Anti-Bacterial Agents; Aorta; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Coated Materials, Biocompatible; Collagen; Disease Models, Animal; Dogs; Escherichia coli; Escherichia coli Infections; Gelatin; Inflammation; Methicillin-Resistant Staphylococcus aureus; Polyesters; Prosthesis Design; Prosthesis-Related Infections; Rifampin; Silver Compounds; Staphylococcal Infections; Time Factors

To study the feasibility and efficacy of experimental laparoscopy in the diagnosis of aortic graft infection in pigs.. Eight pigs had an aortic tube graft implanted and inoculated with either 5 x 10(4) or 10(6) CFU of Staphylococcus aureus ATCC 29213. Laparoscopy was performed after a median of 20 days with debridement and sampling for bacterial culture. Thereafter, the grafts were locally soaked in rifampicin and postoperatively, the pigs received rifampicin and ciprofloxacin orally for two weeks and were then sacrificed.. All pigs developed graft infection. One pig died from severe clostridial septicaemia before laparoscopy could be performed. The remaining pigs had all samples for bacterial culture taken by laparoscopy from the inflamed tissue. The temperature dropped significantly after laparoscopy, and no macroscopic signs of infection presented at autopsy. However, only culture from one pig was without S. aureus at autopsy.. Laparoscopy is a potential diagnostic tool for aortic graft infection and also affords the opportunity to carry out bacteriological sampling and local antibiotic treatment. The efficacy of laparoscopic treatment needs further evaluation.

Topics: Animals; Anti-Bacterial Agents; Aorta; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Ciprofloxacin; Debridement; Disease Models, Animal; Drug Therapy, Combination; Feasibility Studies; Female; Laparoscopy; Prosthesis-Related Infections; Rifampin; Staphylococcal Infections; Swine; Time Factors

We compared the efficacy of quinupristin/dalfopristin versus vancomycin, alone or in combination with rifampicin, in a rabbit model of methicillin-resistant Staphylococcus aureus-induced arthritis. Vancomycin, alone or in combination with rifampicin, and quinupristin/dalfopristin+rifampicin were significantly more effective than quinupristin/dalfopristin alone.

Topics: Animals; Anti-Bacterial Agents; Arthritis, Infectious; Disease Models, Animal; Drug Therapy, Combination; Methicillin Resistance; Microbial Sensitivity Tests; Rabbits; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Vancomycin; Virginiamycin

Rifampicin, an antibacterial drug widely used in the treatment of tuberculosis and leprosy, has recently been reported to have anti-oxidative and anti-apoptotic effects. However, its anti-angiogenic effect has not been investigated. We examined its anti-angiogenic effect on tube formation and proliferation by human umbilical vein endothelial cells (HUVECs) in vitro and on retinal neovascularization in a murine oxygen-induced retinopathy model in vivo. In addition, we explored the potential mechanisms for its anti-angiogenic effect. Rifampicin significantly suppressed HUVEC tube formation and proliferation, and its effects appeared to be mediated at least in part through inhibition of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. Retinal neovasuclarization was induced in neonatal mice by returning the retina to normoxia (21% O2) after exposure to hyperoxia (75% O2) from postnatal day 7 (P7) to P12. Rifampicin was given subcutaneously at 20mg/kg once a day from immediately after hyperoxia (P12) to P16. At P17, flat-mounted retinas were prepared and evaluated for pathological and physiological angiogenesis. Rifampicin significantly suppressed retinal neovascularization (versus vehicle treatment), but revascularization of the capillary-free area did not differ between vehicle and rifampicin treatment. Rifampicin has anti-angiogenic effects in vitro and in vivo, and may be useful as an anti-angiogenic agent in the treatment of retinal neovascularization diseases.

Topics: Angiogenesis Inhibitors; Animals; Body Weight; Cell Proliferation; Cells, Cultured; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Endothelium, Vascular; Humans; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Oxygen; Phosphorylation; Retinal Neovascularization; Rifampin

The treatment of postoperative mediastinitis is very important because of its high morbidity, mortality, and increased hospital stay and hospital costs. The aims of our research were to investigate whether linezolid alone can be an effective treatment agent for methicillin-resistant Staphylococcus aureus (MRSA) mediastinitis, and to determine whether linezolid can provide synergistic activity when given in combination with rifampin.. A partial upper median sternotomy was performed on 70 rats. The animals were divided into seven groups: an uncontaminated control group; an untreated contaminated group; three contaminated groups that received antibiotic therapy with either 25 or 50 mg/kg linezolid twice a day, or rifampin 5 mg/kg twice a day; and two contaminated groups that received a combination therapy consisting of 25 or 50 mg/kg linezolid and rifampin 5 mg/kg twice a day. The antibiotic treatment lasted 7 days. Tissue samples from the upper ends of the sternum and swab specimens of the upper mediastinum were obtained and evaluated microbiologically.. The 25-mg/kg dose of linezolid, either alone or combined with rifampin, was not effective in reducing the bacterial counts in mediastinum and sternum. Quantitative bacterial cultures of mediastinum and sternum were significantly lower in the groups receiving 50 mg/kg linezolid alone or in combination with rifampin compared with the control. Adding of rifampin to linezolid therapy did not result in a significant change in bacterial counts versus linezolid alone.. A high dose of linezolid should be considered as a possible therapeutic agent for the treatment of post-sternotomy infection caused by MRSA.

Topics: Acetamides; Animals; Anti-Bacterial Agents; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Linezolid; Male; Mediastinitis; Methicillin Resistance; Oxazolidinones; Rats; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Surgical Wound Infection

The aim of this study was to develop a specific and sensitive liquid chromatography mass spectrometry (LC/MS) method for the determination of rifampicin and levofloxacin concentrations from infected tissues within teflon catheter segments which were subcutaneously implanted in mice. A solid-phase extraction procedure was used to extract analytes from tissue homogenates of the catheter segments and reverse-phase HPLC combined with positive electrospray ionization mass spectrometry was used for analyte separation and quantification. The assay was found to be linear over the concentration range of 0.02-2 microg/g for rifampicin and levofloxacin in tissues and provided good validation data for accuracy and precision. The intra-day accuracy as determined by the relative error was -1.3% for levofloxacin and 6.1% for rifampicin, and precision was evaluated by R.S.D.s with a maximum of 5.1% for levofloxacin and 8.1% for rifampicin. The inter-day accuracy was -3.3% for levofloxacin and -4.6% for rifampicin, and precision was 8.6% for levofloxacin and 7.1% for rifampicin. The assay uses less tissue than previously described methods and can be applied to determine the penetration of rifampicin and the fluoroquinolone in catheter segments from a mouse model of a device-related infection. Finally, the HPLC-MS assay should be applicable to studies of rifamycin+quinolone combination therapies in other animal models of bacterial infection.

Topics: Animals; Anti-Bacterial Agents; Catheters, Indwelling; Chromatography, High Pressure Liquid; Disease Models, Animal; Levofloxacin; Mice; Mice, Inbred BALB C; Ofloxacin; Rifampin; Sensitivity and Specificity; Spectrometry, Mass, Electrospray Ionization; Staphylococcus aureus

Brucellosis is an important health issue in many parts of the world and clinicians are still seeking for better treatment choices. The aim of this study was to investigate the efficacy of moxifloxacin in an experimental brucellosis model and to compare its activity with rifampicin. Wistar albino rats infected with Brucella abortus were then randomized into 3 groups, which received rifampicin, moxifloxacin, and tap water, respectively. After 21 days, they were sacrificed and spleen, liver and blood cultures were performed. Spleen and liver cultures of all the animals yielded B. abortus in the control group, while these rates were 20% and 20% in the rifampicin group and 50% and 40% in the moxifloxacin group, respectively. The blood culture positivity was 66% in the control group and 10% in the moxifloxacin group. Blood cultures were all negative in the rifampicin group. As a conclusion, moxifloxacin might be an alternative choice in the treatment of brucellosis.

Topics: Animals; Anti-Bacterial Agents; Aza Compounds; Brucellosis; Disease Models, Animal; Fluoroquinolones; Moxifloxacin; Quinolines; Rats; Rats, Wistar; Rifampin

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Drug Approval; Drug Evaluation, Preclinical; Drug Therapy, Combination; Humans; Mice; Rifampin; Tuberculosis; United States; United States Food and Drug Administration

The curing activities of various durations of treatment with a combination of rifampin (RIF) and either streptomycin (STR) or amikacin (AMK) in murine Mycobacterium ulcerans infection were compared in two experiments. In the first experiment, treatment was begun 1 week after infection, when the inflammatory footpad lesion had not yet occurred (preventive model), and in the second experiment, treatment was begun 6 weeks after infection, when inflammatory footpad lesions were established (curative model). In the first experiment, 4 weeks of treatment with daily RIF-STR or RIF-AMK was able to postpone the occurrence of footpad lesion by 12 weeks (RIF-STR) or 17 weeks (RIF-AMK), thus demonstrating their promising bactericidal activities, but neither treatment was able to prevent the late occurrence of footpad lesions. In the second experiment, the overall cure rates, as assessed by the lack of rebound of inflammatory lesions or remultiplication of M. ulcerans, were only 62% after 2 weeks of treatment with RIF and an aminoglycoside and 85% after 4 weeks; but the cure rate reached 100% after 8 or 12 weeks of treatment. The cure rates were slightly higher with the AMK-containing combination than with the STR-containing combination, but the difference was at the limit of significance (P=0.07). These results show that in the murine model of Buruli ulcer, 8 weeks is the optimal duration of treatment with a combination of RIF and an aminoglycoside.

Topics: Amikacin; Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Therapy, Combination; Female; Mice; Mice, Inbred BALB C; Mycobacterium Infections, Nontuberculous; Mycobacterium ulcerans; Rifampin; Streptomycin; Treatment Outcome

We used the ability of Salmonella enterica serovar Typhimurium to colonize the gut of Caenorhabditis elegans to measure the fitness costs imposed by antibiotic resistance mutations. The fitness costs determined in the nematode were similar to those measured in mice, validating its use as a simple host model to evaluate bacterial fitness.

Topics: Animals; Caenorhabditis elegans; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Mice; Salmonella Infections, Animal; Salmonella typhimurium

We compared the efficacy of a novel rifamycin derivative, ABI-0043, with that of rifampin, alone and in combination with levofloxacin, against methicillin-susceptible Staphylococcus aureus ATCC 29213 in a guinea pig tissue-cage infection model. The MIC, logarithmic-growth-phase minimal bactericidal concentration, and stationary-growth-phase minimal bactericidal concentration of ABI-0043 were 0.001, 0.008, and 0.25 microg/ml, respectively; the corresponding concentrations of rifampin were 0.016, 0.8, and 3.6 microg/ml, respectively. After a single intraperitoneal dose of 12.5 mg/kg of body weight, the peak concentration in cage fluid was 1.13 micarog/ml of ABI-0043 and 0.98 microg/ml of rifampin. Five days after completion of treatment, levofloxacin administered alone (5 mg/kg/12 h) resulted in bacterial counts in cage fluid that were similar to those for untreated controls (>8.0 log(10) CFU/ml), whereas rifampin and ABI-0043 administered alone (12.5 mg/kg/12 h) decreased the mean titers of bacteria +/- standard deviations to 1.43 +/- 0.28 log(10) and 1.57 +/- 0.53 log(10) CFU/ml, respectively, in cage fluid. In combination with levofloxacin, both rifamycins cleared bacteria from the cage fluid. The cure rates of cage-associated infections with rifampin and ABI-0043 administered alone were 46% and 58%, respectively, and increased to 88% and 92% in combination with levofloxacin. Emergence of rifamycin resistance was observed in 42% of cages after ABI-0043 therapy and in 38% of cages after rifampin therapy; no emergence of resistance occurred with combination treatment with levofloxacin. In conclusion, ABI-0043 had cure rates comparable to that of rifampin. ABI-0043 in combination with a quinolone has the potential for treatment of implant-associated infections caused by susceptible strains of S. aureus, potentially without drug-drug interactions.

Topics: Animals; Anti-Bacterial Agents; Colony Count, Microbial; Disease Models, Animal; Drug Therapy, Combination; Foreign-Body Reaction; Guinea Pigs; Injections, Intraperitoneal; Levofloxacin; Male; Microbial Sensitivity Tests; Molecular Structure; Ofloxacin; Rifampin; Rifamycins; Staphylococcal Infections; Staphylococcus aureus; Time Factors

The effect of colistin on bacterial eradication and survival was tested in experimental infection by multidrug-resistant Acinetobacter baumannii. The thigh infection model was applied in 86 neutropenic Wistar rats. Six rats were used for the induction of neutropenia and for the selection of the dose regimen of colistin; the remainder was equally divided into four groups: A, controls; B, rifampicin; C, colistin; and D, both agents. Therapy was administered 5 h after bacterial challenge; 5mg/kg of rifampicin was administered intravenously and 3mg/kg of colistin intramuscularly. Survival was recorded in 10 animals of each group. The remaining 10 rats per group were killed 4h after therapy; blood and tissue samples were sampled. Median survival of animals of groups A, B, C and D was 2.00, 2.50, 4.00 and 4.00 days, respectively (P=0.0048 between A and C and P=0.0012 between A and D. Mortality rates after 6 days of follow-up were 100, 100, 100 and 70%, respectively (P=0.018 between groups). Statistically significant decreases of bacteria were found in blood, liver, lung and spleen of group B compared with A; in lung of group C compared with A; and in blood and liver of group D compared with A. Colistin was effective in prolonging survival in an experimental thigh infection by multidrug-resistant A. baumannii in neutropenic rats. Its activity was enhanced after co-administration with rifampicin. These results mandate the application of colistin in the event of infections by multidrug-resistant pathogens and the need for its co-administration with rifampicin.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Blood; Colistin; Cyclophosphamide; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Injections, Intramuscular; Injections, Intravenous; Liver; Lung; Male; Rats; Rats, Wistar; Rifampin; Spleen; Survival Analysis; Survival Rate; Treatment Outcome

A suspension of multidrug resistant clinical Mycobacterium tuberculosis (MBT) strain, at a concentration of 1 x 10(8) microbes per ml, resistant to streptomycin (S), rifampicin (R), isoniazid (I), and kanamycin (K), was in vitro treated for 60 minutes with dissolved ozone (pO3) at a concentration of 0.5-4 microg/ml). Then it was placed in the Lowenstein-Jensen media containing various concentrations of S, I, R, and K. Following 3 months, drug susceptibility was determined by the number of cultured colonies and MBT was used to prepare a suspension at the same concentration, which was again treated with pO3 by the same procedure and placed to the media containing the drugs. A session was thrice repeated. After each pO3 treatment, MBT resistance to I decreased and it completely disappeared after triple treatment. Each pO3 treatment caused a reduction in MBT resistance to R, but it was high (640 microg/ml). After double pO3 treatment MBT resistance to S decreased, but it was recovered after its third ozone treatment. All pO3-untreated control cultures showed a growth of more than 100 colonies. Sixty-eight BALC/s mice were in vivo inoculated via intravenous injections of the clinical MBT strain resistant to S, I, R, and K. The mice were divided into 5 groups: 1) intact mice; 2) those inoculated and untreated; 3) those treated with 1; 4) those treated with I and peritoneally given pO3, 0.5-4 microg/ml); and 5) those given pO3. The animals began dying at month 4 of inoculation. By month 5, all mice, other than intact and pO3-treated ones, died. Passage of MBT from the month by month 4 showed a reduction in their resistance to I in the groups treated with pO3. When the mice were treated with I alone, damages to their livers and spleens were greater than when they were untreated. With co-administration of I and pO3, the damage was least. Treatment provoked a rapid change of MBT to granular and L-forms and MBT was undetectable in its typical form after 1-2-month therapy. The altered MBT formed an untypical histological pattern of tuberculous inflammation in mice in the presence of characteristic cellular cooperation. Clinical studies indicated that 1-6-month concurrent use of chemotherapy and pO3 in patients with drug-resistant tuberculosis eliminated drug resistance of isolated MBT to one of the drugs (I, R, K) in 97.3%, MBT became at once susceptible to I, R, and K in 47.2%. I and/or R were successfully used in the treatment of more than a third of the patients.

Topics: Adolescent; Adult; Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Antitubercular Agents; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Female; Humans; Injections, Intravenous; Isoniazid; Kanamycin; Male; Mice; Mice, Inbred BALB C; Middle Aged; Mycobacterium tuberculosis; Ozone; Radiography, Thoracic; Rifampin; Streptomycin; Time Factors; Treatment Outcome; Tuberculosis, Multidrug-Resistant; Tuberculosis, Pulmonary

A model of leprosy was used to study the therapeutic effect of horse-radish root (HRR) containing peroxidase in combination with rifampicin (RFP) and potassium iodide (PI) as compared to routine combined therapy with RFP and diaminodiphenylsulfonum. Therapy with HRR and iodide showed the best antimicrobial effect than the routine combined therapy. A combination of RFP, HRR, and PI increased the activity of neutrophilic myeliperoxidase produced an anti-inflammatory activity and caused no persistent anemia or toxic effect on the murine liver.

Topics: Animals; Armoracia; Disease Models, Animal; Drug Therapy, Combination; Horseradish Peroxidase; Leprosy; Mice; Mice, Inbred CBA; Neutrophils; Peroxidase; Plant Roots; Potassium Iodide; Rifampin; Treatment Outcome

Availability of an ultra-short-course drug regimen capable of curing patients with tuberculosis in 2 to 3 mo would significantly improve global control efforts. Because immediate prospects for novel treatment-shortening drugs remain uncertain, we examined whether better use of existing drugs could shorten the duration of treatment. Rifapentine is a long-lived rifamycin derivative currently recommended only in once-weekly continuation-phase regimens. Moxifloxacin is an 8-methoxyfluoroquinolone currently used in second-line regimens.. Using a well-established mouse model with a high bacterial burden and human-equivalent drug dosing, we compared the efficacy of rifapentine- and moxifloxacin-containing regimens with that of the standard daily short-course regimen based on rifampin, isoniazid, and pyrazinamide. Bactericidal activity was assessed by lung colony-forming unit counts, and sterilizing activity was assessed by the proportion of mice with culture-positive relapse after 2, 3, 4, and 6 mo of treatment. Here, we demonstrate that replacing rifampin with rifapentine and isoniazid with moxifloxacin dramatically increased the activity of the standard daily regimen. After just 2 mo of treatment, mice receiving rifapentine- and moxifloxacin-containing regimens were found to have negative lung cultures, while those given the standard regimen still harbored 3.17 log10 colony-forming units in the lungs (p < 0.01). No relapse was observed after just 3 mo of treatment with daily and thrice-weekly administered rifapentine- and moxifloxacin-containing regimens, whereas the standard daily regimen required 6 mo to prevent relapse in all mice.. Rifapentine should no longer be viewed solely as a rifamycin for once-weekly administration. Our results suggest that treatment regimens based on daily and thrice-weekly administration of rifapentine and moxifloxacin may permit shortening the current 6 mo duration of treatment to 3 mo or less. Such regimens warrant urgent clinical investigation.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Aza Compounds; Colony Count, Microbial; Disease Models, Animal; Drug Administration Schedule; Drug Therapy, Combination; Fluoroquinolones; Isoniazid; Lung; Mice; Mice, Inbred BALB C; Moxifloxacin; Mycobacterium tuberculosis; Pyrazinamide; Quinolines; Rifampin; Secondary Prevention; Time Factors; Tuberculosis

To evaluate the role of mitochondrial oxidative stress and permeability transition (MPT) in isoniazid (INH) and rifampicin (RMP) induced hepatotoxicity in mice.. Liver damage was induced by co-treatment of INH (50 mg/kg) and RMP (100 mg/kg). Pre-treatment with either methionine or phorone was done to modulate hepatic GSH level. Liver cell injury was assessed biochemically and histologically. Evidence of apoptosis was sought by TUNEL test, caspase assay and histology.. INH and RMP co-treatment caused steatosis and increased apoptosis of the hepatocytes, hepatic oxidative stress, particularly in the mitochondrial fraction with increased mitochondrial permeability transition (MPT). Mitochondrial oxidative stress as well as liver cell injury was increased by prior treatment with phorone. This was attenuated by pretreatment with methionine suggesting a glutathione (GSH) dependent phenomenon.. Oxidative stress in the mitochondria and inappropriate MPT are important in the pathogenesis of apoptotic liver cell injury in INH-RMP hepatotoxicity. The phenomenon is GSH dependent and methionine supplementation might have a protective role.

Topics: Animals; Disease Models, Animal; Fatty Liver; Glutathione; Isoniazid; Liver; Male; Mice; Mice, Inbred BALB C; Mitochondria, Liver; Mitochondrial Membranes; Oxidative Stress; Permeability; Rifampin

We investigated the protective role of immune-sera against reactivation of Mycobacterium tuberculosis infection in SCID mice and found that passive immunization with sera obtained from mice treated with detoxified M. tuberculosis extracts (delivered in liposomes in a composition known as RUTI) exerted significant protection. Our SCID mouse model consisted of aerosol infection by M. tuberculosis, followed by 3 to 8weeks of chemotherapy with isoniazid+rifampicin (INH+RIF) (25 and 10mg/kg, respectively). After infection and antibiotic administration, two groups of mice were treated for up to 10weeks with intraperitoneal passive immunization using hyperimmune serum (HS) obtained from mice infected with M. tuberculosis, treated with chemotherapy (INH+RIF) for 8weeks and inoculated with RUTI (HS group) or with normal serum (CT group). Significant differences were found between HS and CT groups in the number of bacilli in the lungs (3.68+/-2.02 vs. 5.72+/-1.41log(10) c.f.u.), extent of pulmonary granulomatomous infiltration (10.33+/-0.67 vs. 31.2+/-1.77%), and percentage of animals without pulmonary abscesses (16.7% vs. 45.5%). These data strongly suggest a protective role of specific antibodies against lung dissemination of M. tuberculosis infection.

Topics: Animals; Antibodies, Bacterial; Antitubercular Agents; Disease Models, Animal; Female; Humans; Immune Sera; Immunization, Passive; Isoniazid; Lung; Mice; Mice, Inbred DBA; Mice, SCID; Mycobacterium tuberculosis; Rifampin; Secondary Prevention; Specific Pathogen-Free Organisms; Tuberculosis

To examine the development of rifampicin resistance in multidrug-resistant Acinetobacter baumannii exposed to rifampicin and the prevention of the appearance of rifampicin-resistant mutants when rifampicin is used in association with imipenem or sulbactam.. A clinical strain of multidrug-resistant A. baumannii was used to examine the frequency of resistance to rifampicin in vivo, in a pneumonia model in immunocompetent C57BL/6 mice. The in vitro and in vivo prevention of the development of resistance to rifampicin was analysed using rifampicin alone or in association with imipenem or sulbactam, in time-kill studies and in the experimental murine pneumonia, respectively.. Rifampicin-resistant mutants were found at 48 and 72 h, both in vitro and in vivo, when rifampicin was used alone, with the MIC increasing from 4 to > or =128 mg/L. The in vivo frequency of rifampicin-resistant mutants was 3 x 10(-6). On the contrary, no resistant mutants appeared after 72 h, in vitro or in vivo, when rifampicin was employed in association with imipenem or sulbactam. After six daily passages in rifampicin-free agar plates the resistant mutants maintained the high resistance to rifampicin (> or =128 mg/L).. These results suggest that rifampicin must not be used alone in the treatment of infections caused by multidrug-resistant A. baumannii. In these cases, rifampicin may be used in combination with imipenem or sulbactam, which prevent the development of resistance to rifampicin.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Drug Therapy, Combination; Female; Imipenem; Mice; Mice, Inbred C57BL; Microbial Sensitivity Tests; Mutation; Pneumonia, Bacterial; Rifampin; Sulbactam

The creation of new chemotherapeutic regimens that permit shortening the duration of treatment is a major priority for antituberculosis drug development. In this study, we used the murine model of experimental tuberculosis therapy to determine whether incorporation of the investigational new nitroimidazopyran PA-824 into the standard first-line regimen has the potential to shorten the 6-month duration of treatment. As demonstrated previously, PA-824 alone had significant bactericidal activity over the first 2 months of treatment. Moreover, the substitution of PA-824 for isoniazid led to significantly lower lung CFU counts after 2 months of treatment and to more rapid culture-negative conversion compared to the standard regimen of rifampin, isoniazid, and pyrazinamide. Despite this, there was no difference in the proportion of mice relapsing after completing 6 months of therapy (2 of 19 mice treated with PA-824 in place of isoniazid relapsed versus 0 of 46 mice treated with the standard regimen). Meanwhile, no other PA-824-containing regimen tested was superior to the standard regimen on any assessment. Thus, we were unable to establish a clear role for PA-824 in a treatment-shortening regimen that includes two or more of the current first-line drugs. Future preclinical studies should include the evaluation of novel combinations of PA-824 with new drug candidates in addition to existing antituberculosis drugs for their potential to substantially improve the treatment of both drug-susceptible and multidrug-resistant tuberculosis.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Disease Models, Animal; Drug Therapy, Combination; Ethambutol; Female; Isoniazid; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Nitroimidazoles; Pyrazinamide; Rifampin; Secondary Prevention; Time Factors; Tuberculosis, Pulmonary

Antimicrobial efficacy in orthopedic device infections is diminished because of bacterial biofilms which express tolerance to antibiotics. Recently, the use of high doses of levofloxacin with rifampin has been recommended for staphylococcal infections. In the present study, we evaluated the efficacy of levofloxacin at doses of 50 mg/kg/day and 100 mg/kg/day (mimicking the usual and high human doses of 500 mg/day and 750 to 1,000 mg/day, respectively) and compared it to that of to linezolid, cloxacillin, vancomycin, and rifampin in a rat tissue cage model of experimental foreign-body infection by Staphylococcus aureus. The antimicrobial efficacy in vitro (by MIC, minimum bactericidal concentration, and kill curves) for logarithmic- and stationary-phase bacteria was compared with the in vivo efficacy. In vitro bactericidal activity at clinically relevant concentrations was reached by all drugs except rifampin and linezolid in the log-phase studies but only by levofloxacin in the stationary-phase studies. The bacterial count decreases from in vivo tissue cage fluids (means) for levofloxacin at 50 and 100 mg/kg/day, rifampin, cloxacillin, vancomycin, linezolid, and controls, respectively, were: -1.24, -2.26, -2.1, -1.56, -1.47, -1.15, and 0.33 (all groups versus controls, P < 0.05). Levofloxacin at 100 mg/kg/day (area under the concentration-time curve/MIC ratio, 234) was the most active therapy (P = 0.03 versus linezolid). Overall, in vivo efficacy was better predicted by stationary-phase studies, in which it reached a high correlation coefficient even if the rifampin group was excluded (r = 0.96; P < 0.05). Our results, including in vitro studies with nongrowing bacteria, pharmacodynamic parameters, and antimicrobial efficacy in experimental infection, provide good evidence to support the use of levofloxacin at high doses (750 to 1,000 mg/day), as recently recommended for treating patients with orthopedic prosthesis infections.

Topics: Acetamides; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Cloxacillin; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Foreign-Body Reaction; Humans; Levofloxacin; Linezolid; Male; Methicillin; Microbial Sensitivity Tests; Ofloxacin; Oxazolidinones; Rats; Rats, Wistar; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Vancomycin

To investigate the presence of rifampicin-dependent Mycobacterium tuberculosis strains by use of a guinea pig model of tuberculosis of rifampicin-dependent Mycobacterium tuberculosis.. Guinea pigs were randomly divided into groups of infection by rifampicin-dependent Mycobacterium tuberculosis strains (1130 strain, 1219 strain, b858 strain), rifampicin-resistant Mycobacterium tuberculosis strain (1290 strain) and ATCC 35810 strain and each group was further divided into an experimental group and a control group. The guinea pigs were challenged with 1130 strain, 1219 strain, b858 strain, 1290 strain and ATCC 35810 strain to establish the tuberculosis model. The experimental groups were treated with rifampicin. The parameters including macroscopic visceral pathological change index, visceral weight index (spleen, lungs and liver), the colony-forming units (CFU) quantity of visceral Mycobacterium tuberculosis culture (spleen, lungs) and tissue pathology of guinea pigs were observed.. At the 7th week after challenged with 1130 strain, 1219 strain, 1290 strain and b858 strain, all animals were sacrificed. The macroscopic visceral pathological change indices of the experimental group were 68.7 +/- 13.8, 60.0 +/- 13.5, 70.0 +/- 5.8 and 23.8 +/- 18.9, whereas all those parameters of the control group were 76.2 +/- 18.9, 40.0 +/- 16.8, 63.8 +/- 10.3 and 22.5 +/- 15.5 respectively, and there was no significance between the experimental group and the control group (t = 0.64, 1.85, 0.35 and 0.10, all P > 0.05). The spleen weight indices of experimental group were 0.229 +/- 0.048, 0.256 +/- 0.067, 0.324 +/- 0.054 and 0.199 +/- 0.029, whereas all those parameters of control groups were 0.278 +/- 0.025, 0.216 +/- 0.076, 0.368 +/- 0.033 and 0.213 +/- 0.038 respectively, and there was no significance between the experimental group and the control group (t = 1.75, 0.79, 1.41 and 0.57, all P > 0.05). The CFU quantity of spleen Mycobacterium tuberculosis culture of the experimental group were 4.98 +/- 0.30, 4.68 +/- 1.26, 5.07 +/- 0.47 and 3.85 +/- 0.45, whereas all those parameters of control groups were 4.90 +/- 1.03, 4.79 +/- 0.45, 5.08 +/- 0.55 and 4.23 +/- 0.95 respectively, and there was no significance between the experimental group and the control group (t = 0.11, 0.15, 0.03 and 0.73, all P > 0.05); Moreover, the tissue pathology of both groups was similar.. The tuberculosis model of rifampicin-dependent Mycobacterium tuberculosis strains was similar to the model of rifampicin-resistant Mycobacterium tuberculosis in guinea pigs. Rifampicin-dependency was not evident in this guinea pig tuberculosis model.

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Female; Guinea Pigs; Mycobacterium tuberculosis; Rifampin; Tuberculosis

Reduction of colony forming units by rifampicin-isoniazid therapy given 9-17 weeks post-infection was made more pronounced by immunotherapy with a vaccine made of fragmented Mycobacterium tuberculosis cells detoxified and liposomed (RUTI), given on weeks 17, 19 and 21 post-infection, in the murine model of tuberculosis in C57BL/6 and DBA/2 inbred strains. RUTI triggered a Th1/Th2 response, as demonstrated by the production of IgG1, IgG2a and IgG3 antibodies against a wide range of peptides. The histological analysis did not show neither eosinophilia nor necrosis, and granulomatous infiltration was only slightly increased in C57BL/6 mice when RUTI was administered intranasally.

Topics: Animals; Antibodies, Bacterial; Antitubercular Agents; Colony Count, Microbial; Combined Modality Therapy; Disease Models, Animal; Female; Immunoglobulin G; Immunotherapy; Interferon-gamma; Isoniazid; Lung; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; Mycobacterium tuberculosis; Rifampin; Spleen; Tuberculosis; Tuberculosis Vaccines; Tumor Necrosis Factor-alpha

Staphylococcus aureus is the most common organism isolated in osteomyelitis. Methicillin-resistant S. aureus (MRSA) infections are particularly difficult to treat. We evaluated the efficacy of tigecycline and vancomycin with and without rifampicin in a rabbit model of MRSA osteomyelitis.. A 28 day antibiotic therapy with a subcutaneous injection of tigecycline (14 mg/kg twice daily), with and without oral rifampicin (40 mg/kg twice daily); or subcutaneous administration of vancomycin (30 mg/kg twice daily), with and without oral rifampicin (40 mg/kg twice daily) were compared. Osteomyelitis was induced with an intramedullary injection of 10(6) colony-forming units of MRSA. Infected rabbits were randomly divided into six groups: tigecycline, tigecycline with oral rifampicin, vancomycin, vancomycin with oral rifampicin, and no treatment control and tigecycline bone penetration groups. Treatment began 2 weeks after infection. After 4 weeks of therapy, the rabbits were left untreated for 2 weeks. Rabbits were then euthanized, and the tibias were harvested. The bones were cultured, and bacterial counts of MRSA were performed.. Rabbits that received tigecycline and oral rifampicin therapy (n=14) showed a 100% infection clearance. Rabbits treated with tigecycline (n=10) showed a 90% clearance. Rabbits treated with vancomycin and oral rifampicin (n=10) also showed a 90% clearance. Rabbits treated with vancomycin (n=11) showed an 81.8% clearance. Untreated controls (n=15) demonstrated only a 26% clearance. For the tigecycline bone penetration group, the bone concentrations of tigecycline in the infected tibia were significantly higher than the non-infected ones.. Tigecycline may be an effective alternative to vancomycin in the treatment of MRSA osteomyelitis.

Topics: Animals; Bone and Bones; Disease Models, Animal; Drug Therapy, Combination; Methicillin Resistance; Minocycline; Osteomyelitis; Rabbits; Radiography; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Tigecycline; Vancomycin

The emergence of drug-resistant bacteria poses a serious threat to human health. In the case of several antibiotics, including those of the quinolone and rifamycin classes, bacteria rapidly acquire resistance through mutation of chromosomal genes during therapy. In this work, we show that preventing induction of the SOS response by interfering with the activity of the protease LexA renders pathogenic Escherichia coli unable to evolve resistance in vivo to ciprofloxacin or rifampicin, important quinolone and rifamycin antibiotics. We show in vitro that LexA cleavage is induced during RecBC-mediated repair of ciprofloxacin-mediated DNA damage and that this results in the derepression of the SOS-regulated polymerases Pol II, Pol IV and Pol V, which collaborate to induce resistance-conferring mutations. Our findings indicate that the inhibition of mutation could serve as a novel therapeutic strategy to combat the evolution of antibiotic resistance.

Topics: Animals; Bacterial Proteins; Ciprofloxacin; Disease Models, Animal; DNA Damage; DNA, Bacterial; Drug Resistance; Drug Resistance, Bacterial; Escherichia coli; Escherichia coli Infections; Evolution, Molecular; Mice; Microbial Sensitivity Tests; Mutation; Repressor Proteins; Rifampin; Serine Endopeptidases

Besides the long-term effectiveness of a given compound, safety is a very important feature to consider when developing new compounds for chemotherapy against tuberculosis. Reports of fatal and severe liver injury associated with rifampicin-pyrazinamide (RIF-PZA) treatment regimens for latent tuberculosis infections prompted this study to evaluate whether a mouse model has any potential as a tool to assess liver injury following extensive exposure to tuberculosis drugs. Mice were administered high doses of existing drug regimens for latent tuberculosis over a relatively short time period. Alanine aminotransferase (ALT), aspartate aminotransferase and bilirubin levels were determined after 2 weeks and 4 weeks of treatment in serum samples collected from uninfected mice as well as mice infected with Mycobacterium tuberculosis. ALT levels increased significantly after a RIF-PZA treatment regimen for 4 weeks in uninfected mice and after 2 weeks in infected mice. Bilirubin serum levels were also significantly elevated in the M. tuberculosis-infected mice after 4 weeks of RIF-PZA treatment. The data obtained indicate that changes in serum enzyme levels in mice after extensive exposure to tuberculosis drugs could be useful as an initial indicator of drug-related hepatotoxicity.

Topics: Alanine Transaminase; Animals; Antitubercular Agents; Disease Models, Animal; Drug Therapy, Combination; Liver; Pyrazinamide; Rifampin; Tuberculosis

This study was planned to compare the efficacy of ceftriaxone+vancomycin with ceftriaxone+rifampicin in a rabbit model of penicillin and cephalosporin-resistant Streptococcus pneumoniae meningitis. Meningitis was induced by intracisternal inoculation of S. pneumoniae. After 18 h of incubation, Group 1 was given saline solution (control group), whilst Groups 2 and 3 were given ceftriaxone+vancomycin and ceftriaxone+rifampicin, respectively. Cerebrospinal fluid bacterial concentrations were measured at 0, 2, 12, 14 and 24 h after therapy was initiated. In the control group, bacterial growth was present at all time points, whereas no growth was observed in either the ceftriaxone+vancomycin group or the ceftriaxone+rifampicin group after 2 h of therapy. Ceftriaxone+rifampicin was found to be as effective as ceftriaxone+vancomycin in the treatment of penicillin-resistant S. pneumoniae meningitis in experimental rabbit model.

Topics: Animals; Anti-Bacterial Agents; Ceftriaxone; Cephalosporin Resistance; Cerebrospinal Fluid; Disease Models, Animal; Drug Resistance, Bacterial; Drug Therapy, Combination; Meningitis, Meningococcal; Penicillin Resistance; Rabbits; Rifampin; Streptococcus pneumoniae; Vancomycin

Treatment of tuberculosis with an efficacious once-weekly regimen would be a significant achievement in improving patient adherence. Currently, the only recommended once-weekly continuation phase regimen of isoniazid plus rifapentine (10 mg/kg) is inferior to standard twice-weekly therapy with isoniazid plus rifampin and is, therefore, restricted to non-high-risk patients. The substitution of moxifloxacin, a new 8-methoxyfluoroquinolone, for isoniazid and an increase in the dose of rifapentine could augment the activity of once-weekly regimens.. To test this hypothesis we evaluated the sterilizing activity of improved once-weekly rifapentine-based continuation phase regimens in a murine model that mimics the treatment of high-risk patients with tuberculosis. The bactericidal activity of standard daily therapy and standard intermittent therapy ("Denver" regimen) was also assessed to evaluate the effect of intermittent drug administration during the initial phase of therapy.. After 2 mo of treatment, lung colony-forming unit counts were 1 log(10) lower in mice treated with standard daily therapy than with the Denver regimen. During the continuation phase, the sterilizing activity of once-weekly moxifloxacin plus rifapentine (15 mg/kg) was significantly greater than that of the predominantly twice-weekly Denver regimen of isoniazid plus rifampin. No significant difference in sterilizing activity was detected between once-weekly isoniazid plus rifapentine (15 mg/kg) and the Denver regimen.. These results suggest that the efficacy of the once-weekly isoniazid plus rifapentine continuation phase regimen can be increased by substituting moxifloxacin for isoniazid and by increasing the dose of rifapentine to a clinically acceptable level of 15 mg/kg.

Topics: Animals; Antibiotics, Antitubercular; Aza Compounds; Colony Count, Microbial; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Drug Therapy, Combination; Female; Fluoroquinolones; Follow-Up Studies; Lung; Mice; Mice, Inbred BALB C; Moxifloxacin; Mycobacterium tuberculosis; Quinolines; Rifampin; Treatment Outcome; Tuberculosis, Pulmonary

Priorities for developing improved regimens for treatment of latent tuberculosis (TB) infection include (1) developing shorter and/or more intermittently administered regimens that are easier to supervise and (2) developing and evaluating regimens that are active against multidrug-resistant organisms.. By using a previously validated murine model that involves immunizing mice with Mycobacterium bovis bacillus Calmette-Guérin to augment host immunity before infection with virulent Mycobacterium tuberculosis, we evaluated new treatment regimens including rifapentine and moxifloxacin, and assessed the potential of the Mycobacterium leprae heat shock protein-65 DNA vaccine to augment the activity of moxifloxacin.. Quantitative spleen colony-forming unit counts, and the proportion of mice with culture-positive relapse after treatment, were determined.. Three-month, once-weekly regimens of rifapentine combined with either isoniazid or moxifloxacin were as active as daily isoniazid for 6-9 mo. Six-month daily combinations of moxifloxacin with pyrazinamide, ethionamide, or ethambutol were more active than pyrazinamide plus ethambutol, a regimen recommended for latent TB infection after exposure to multidrug-resistant TB. The combination of moxifloxacin with the experimental nitroimidazopyran PA-824 was especially active. Finally, the heat shock protein-65 DNA vaccine had no effect on colony-forming unit counts when given alone, but augmented the bactericidal activity of moxifloxacin.. Together, these findings suggest that rifapentine, moxifloxacin, and, perhaps, therapeutic DNA vaccination have the potential to improve on the current treatment of latent TB infection.

Topics: Animals; Antibiotics, Antitubercular; Aza Compounds; Colony Count, Microbial; Disease Models, Animal; Drug Therapy, Combination; Female; Fluoroquinolones; Follow-Up Studies; Mice; Mice, Inbred BALB C; Moxifloxacin; Mycobacterium tuberculosis; Quinolines; Rifampin; Spleen; Treatment Outcome; Tuberculosis; Vaccines, DNA

The aim of the study was to assess the in vitro and in vivo efficacy of ceftriaxone, vancomycin and rifampicin alone and combined against Streptococcus pneumoniae ATCC 51916 (MIC of ceftriaxone: 32 mg/L).. In vitro killing curves were performed with clinically achievable CSF antibiotic concentrations. In the rabbit model of pneumococcal meningitis, we studied the efficacy of and effects on inflammation of treatment with ceftriaxone 100 mg/kg/day, vancomycin 30 mg/kg/day and rifampicin 15 mg/kg/day, alone and combined, over a 26 h period.. Time-kill curves showed that vancomycin was bactericidal, and ceftriaxone and rifampicin produced a bacteriostatic effect. An additive effect was observed when combinations of ceftriaxone plus vancomycin were studied at subinhibitory concentrations. Emergence of resistance to rifampicin was detected both when rifampicin was studied alone and when combined with ceftriaxone or vancomycin. In the rabbit meningitis model, ceftriaxone was bacteriostatic, whereas rifampicin and vancomycin were bactericidal at 24 h. Although not synergistic, the combinations of ceftriaxone plus vancomycin or rifampicin, and vancomycin plus rifampicin, improved the efficacy of any antibiotic tested alone--all combinations were bactericidal from 6 h--and significantly decreased inflammatory parameters in CSF compared with control and ceftriaxone groups.. Ceftriaxone plus vancomycin, and vancomycin plus rifampicin appeared to be effective in the therapy of experimental pneumococcal meningitis caused by highly cephalosporin-resistant strains such as ATCC 51916. Our results provide an experimental basis for using these combinations as empirical therapy for pneumococcal meningitis, regardless of the degree of cephalosporin resistance of the causative strain.

Topics: Animals; Ceftriaxone; Cephalosporin Resistance; Cerebrospinal Fluid; Colony Count, Microbial; Disease Models, Animal; Drug Combinations; Drug Interactions; Drug Resistance, Bacterial; Female; Meningitis, Pneumococcal; Microbial Sensitivity Tests; Rabbits; Rifampin; Streptococcus pneumoniae; Vancomycin

A model of Brucella melitensis infection was used in the setting of long-term ethanol administration to study the effects of ethanol on antibiotic therapy of B. melitensis infection. Wistar rats received a liquid diet containing maximally 42.2% of total calories as ethanol. Controls were pair-fed a liquid diet without ethanol. Diets began 15 days pre- and continued post-infection. Rats were infected intraperitoneally with B. melitensis. Doxycycline (10 mg/kg/day) plus rifampicin (6 mg/kg/day) were administered intragastrically starting days 7 to 14 following B. melitensis inoculation. The cure rate was 64.71% in ethanol-fed and 100% in control groups. Although the number of B. melitensis in spleens and livers was reduced, cure was unsuccessful in 6 ethanol-fed rats and this was not explained by the appearance of resistance, since none of the strains isolated following a 7-day course of therapy showed an increase in the minimum inhibitory concentration (MIC) of antibiotics. This study suggests that long-term ethanol ingestion diminishes the efficacy of doxycycline plus rifampicin combination therapy of rat brucellosis in an experimental design.

Topics: Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Brucella melitensis; Brucellosis; Central Nervous System Depressants; Diet; Disease Models, Animal; Doxycycline; Drug Interactions; Ethanol; Microbial Sensitivity Tests; Rats; Rats, Wistar; Rifampin

To investigate the prophylactic efficacy of systemic, topical, or combined antibiotic usage in the prevention of late prosthetic vascular graft infection caused by methicillin-resistant Staphylococcus epidermidis (MRSE) and the differential adherence of S. epidermidis to Dacron and ePTFE grafts in a rat model.. Graft infections were established in the back subcutaneous tissue of 120 adult male Wistar rats by implantation of 1-cm(2) Dacron/ePTFE prosthesis followed by topical inoculation with 2 x 10(7) CFU of clinical isolate of MRSE. Each of the series included one group with no graft contamination and no antibiotic prophylaxis (uncontaminated control), one contaminated group that did not receive any antibiotic prophylaxis (untreated control), one contaminated group in which perioperative intraperitoneal prophylaxis with vancomycin (10 mg/kg) was administered, two contaminated groups that received rifampicin-soaked (5 mg/1 ml) or vancomycin-soaked (1 mg/1 ml) grafts, and one contaminated group that received a combination of rifampicin-soaked (5 mg/1 ml) graft with perioperative intraperitoneal vancomycin prophylaxis (10 mg/kg). The grafts were removed sterilely 7 days after implantation and evaluated by using sonication and quantitative blood agar culture.. MRSE had significantly greater adherence to Dacron than ePTFE grafts in the untreated contaminated groups (P < 0.001). Rifampicin had better efficacy than vancomycin in topical application, but the difference was not statistically significant (P > 0.05). Intraperitoneal vancomycin showed a significantly higher efficacy than topical vancomycin or rifampicin (P < 0.001). The best results were provided by a combination of intraperitoneal vancomycin in rifampicin-soaked graft groups (P < 0.001).. The combination of rifampicin and intraperitoneal vancomycin seems to be the best choice for the prophylaxis of late prosthetic vascular graft infections caused by MRSE.

Topics: Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Blood Vessel Prosthesis; Blood Vessel Prosthesis Implantation; Disease Models, Animal; Drug Therapy, Combination; Male; Methicillin Resistance; Polyethylene Terephthalates; Polytetrafluoroethylene; Rats; Rats, Wistar; Rifampin; Staphylococcal Infections; Staphylococcus epidermidis; Vancomycin

A lab-scale method for preparation of rifampicin-loaded polybutylcyanoacrylate nanoparticles (nanosames) was developed. The biodistribution of the nanosome-entrapped rifampicin after its intravenous administration was studied on healthy mice. The nanoparticles provided significant liver and spleen accumulation of rifampicin. Modification of the nanoparticles surface with poloxamer 407 or poloxamine 908 led to optimization of the biodistribution: the concentrations of rifampicin in the lungs and plasma increased, whereas the liver accumulation decreased vs. the unmodified nanoparticles. The increased lung accumulation of rifampicin enhanced bacterial clearance in the lungs of the mice infected with M. tuberculosis. The results showed that the use of the nanoparticles for optimization of the drug biodistribution was effective for increasing the efficacy of antiinfective chemotherapy.

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Injections, Intravenous; Male; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Nanostructures; Nanotechnology; Rifampin; Tuberculosis

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Guinea Pigs; Humans; Isoniazid; Liposomes; Mycobacterium tuberculosis; Rifampin; Treatment Outcome; Tuberculosis, Pulmonary

To detect Mycobacterium tuberculosis (MBT) DNA in the blood and organs of tuberculosis-infected animals treated by the standard regimen including 3 first-line drugs, to assess the cellular reactions of organs of MBT-infected mice, and to evaluate the effect of rifampicin supplemented to the Cornell treatment regimen on the occurrence of endogenous reactivation of a tuberculous process, 150 BALB/c mice were intravenously infected with the MTB H(3)7Rv strain in a dose of 2.5 x 10(4) CFU/mouse and given chemotherapy with 3 drugs: rifampicin, 12 mg/kg body weight, isoniazid, 5 mg/kg, and pyrazinamide, 35 mg/kg. On day 20 of infection 2, 4, and 6 months after treatment and 2 months after termination of 4- and 6-month courses of therapy, the authors made inoculation, impressionsmears from parenchymatous organs stained by the Romanovsky-Gimse method, and conducted polymerase chain reaction for MBT DNA in the blood and organs of mice. The results indicated that supplementation of rifampicin to the Cornell treatment regimen prevented endogenous reactivation of the process, as confirmed by negative inoculations of the organs of the mice left untreated for 2 months. However, detection of MBT DNA and the cytological picture characteristic of tuberculous inflammation in the blood and organs of mice from these groups suggested that an occult tuberculous process was preserved.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Disease Models, Animal; DNA, Bacterial; Drug Therapy, Combination; Isoniazid; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Polymerase Chain Reaction; Pyrazinamide; Rifampin; Time Factors; Tuberculosis

Mycobacterium tuberculosis residing within pulmonary granulomas and cavities represents an important reservoir of persistent organisms during human latent tuberculosis infection. We present a novel in vivo model of tuberculosis involving the encapsulation of bacilli in semidiffusible hollow fibers that are implanted subcutaneously into mice. Granulomatous lesions develop around these hollow fibers, and in this microenvironment, the organisms demonstrate an altered physiologic state characterized by stationary-state colony-forming unit counts and decreased metabolic activity. Moreover, these organisms show an antimicrobial susceptibility pattern similar to persistent bacilli in current models of tuberculosis chemotherapy in that they are more susceptible to the sterilizing drug, rifampin, than to the bactericidal drug isoniazid. We used this model of extracellular persistence within host granulomas to study both gene expression patterns and mutant survival patterns. Our results demonstrate induction of dosR (Rv3133c) and 20 other members of the DosR regulon believed to mediate the transition into dormancy, and that rel(Mtb) is required for Mycobacterium tuberculosis survival during extracellular persistence within host granulomas. Interestingly, the dormancy phenotype of extracellular M. tuberculosis within host granulomas appears to be immune mediated and interferon-gamma dependent.

Topics: Animals; Cell Survival; Disease Models, Animal; Female; Gene Expression Regulation, Bacterial; Granuloma; Isoniazid; Mice; Mice, Hairless; Mice, Inbred BALB C; Mutation; Mycobacterium tuberculosis; Oligonucleotide Array Sequence Analysis; Phenotype; Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; Rifampin; Time Factors; Up-Regulation

In situ replacement of infected vascular grafts is an accepted alternative to total graft excision and extraanatomic replacement. Its success relies upon the ability of the newly inserted graft to resist recurrent infection. This study compares the efficacy of two methods used to reduce the risk of graft reinfection: rifampicin soaking versus silver bonding of grafts. The grafts' resistance to infection was tested in vitro in two protocols, each using a panel of seven common bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). The length of time the grafts remained free of organisms was compared between the groups. Both the silver graft and the rifampicin-soaked graft were significantly better than control graft at preventing bacterial growth on the graft surface. The rifampicin inhibited the growth of the gram-positive organisms, including MRSA, significantly better than the silver graft on days 2 and 3 (p < 0.001). Conversely, the silver graft was significantly more effective against the gram-negative organisms until day 4 (p < 0.0001). Both types of graft inhibit the in vitro growth of bacteria more effectively than controls, with rifampicin being most effective against gram-positive organisms and silver being best against the gram-negative organisms.

Topics: Acetates; Animals; Antibiotics, Antitubercular; Blood Vessel Prosthesis Implantation; Coated Materials, Biocompatible; Disease Models, Animal; Escherichia coli Infections; Horses; Methicillin Resistance; Models, Cardiovascular; Prosthesis Design; Prosthesis-Related Infections; Rifampin; Silver Compounds; Staphylococcal Infections; Time Factors

We report the role of human neutrophil peptide (HNP)-1 as an adjunct to antituberculosis (anti-TB) drugs. The combination of HNP-1, isoniazid, and rifampicin was evaluated against Mycobacterium tuberculosis H(37)Rv in vitro, ex vivo, and in vivo, and synergism was observed on the basis of reductions in minimum inhibitory concentrations (MICs) of these agents. In vitro results revealed >1-log unit reductions even when HNP-1 and anti-TB drugs were used at 1/16 MICs. This combination was also found to be bactericidal against intracellular mycobacteria even at 1/8 MICs of HNP-1 and drugs. HNP-1 used in conjunction with anti-TB drugs resulted in significant clearance of bacterial load from lungs, liver, and spleen of infected, compared with control animals. The effective therapeutic dosage of drugs could be reduced to half by supplementing HNP-1 in the therapeutic schedule. These results clearly suggest that HNP-1 can be used as adjunct chemotherapy with conventional drugs against TB.

Topics: alpha-Defensins; Animals; Anti-Infective Agents; Antitubercular Agents; Cell Line; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Therapy, Combination; Female; Isoniazid; Male; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Rifampin; Tuberculosis

Successful therapy of carbapenem-resistant Acinetobacter baumannii strains has been reported with colistin, but recently we argued against its use as monotherapy because of the poor results obtained in a mouse pneumonia model. Our aim was to identify antibiotic combinations that were valid therapeutic alternatives in the same model.. We used two carbapenem-resistant A. baumannii strains (D and E; MICs of imipenem, 8 and 512 mg/L, respectively). MICs of tobramycin, rifampicin and colistin for both strains were 8, 8 and 0.5 mg/L, respectively.. In infections caused by strain D, lung bacterial counts (log(10) cfu/g, mean +/- s.d.) were: controls (10.86+/-0.25), imipenem (5.99+/-0.59, P < 0.05 versus controls), and colistin (10.43 +/- 1.09); imipenem + tobramycin was the most active combination (5.46+/-0.62, P < 0.05 versus controls). In infections caused by strain E, results were: controls (10.82+/-0.33), rifampicin (5.62+/-0.26, P < 0.05 versus controls), colistin (8.38+/-1.22, P < 0.05 versus controls), and imipenem (11.01+/-0.2); rifampicin + imipenem (3.79+/-0.99) and rifampicin + tobramycin (3.96+/-0.30) were the most active combinations (P < 0.05); results with rifampicin + colistin (5.59+/-1.17) were similar to those with rifampicin alone.. Our data indicate that imipenem can still be the best alternative for carbapenem-resistant A. baumannii infections with moderate levels of imipenem resistance, preferably combined with aminoglycosides. For strains highly resistant to imipenem, a combination of rifampicin with imipenem, tobramycin or colistin may be useful, if resistance to rifampicin is only moderate.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Animals; Anti-Bacterial Agents; beta-Lactams; Carbapenems; Colistin; Disease Models, Animal; Drug Resistance, Bacterial; Drug Therapy, Combination; Female; Humans; Mice; Mice, Inbred C57BL; Microbial Sensitivity Tests; Pneumonia, Bacterial; Rifampin; Tobramycin

Concentrations of the calcium-binding proteins of the S100 family, myeloid-related proteins 8 and MRP 14 (MRP8/14), are elevated in chronic infections, yet the role of these proteins is not clearly defined. Using commercial and developed enzyme immunoassays, we assayed for MRP8/14 in sterile-filtered abscess fluid from tissue-cage-implanted rats and rabbits. Staphylococcus aureus abscesses were created 6 weeks after the intraperitoneal implantation of tissue cages. Leukocytes, bacteria, and non-protein-bound calcium and zinc were measured in the infection exudate at day 3 or 5 of infection and after 8 days of treatment with antimicrobials beta-lactams (18 rabbits, 35 rats) and fluoroquinolone-rifampin (6 rabbits). Half of the infected rats were depleted of neutrophils; these rats exhibited significantly lower MRP 8/14 concentrations on all days sampled, regardless of the level of infection. The level of abscess MRP 8/14 is high early in the course of infection but decreases with effective antimicrobial treatment by as much as 100-fold. Thirty-day-old abscesses with log 6 bacterial counts and low neutrophil counts showed low concentrations of MRP 8/14 in these models. In abscess fluid, interleukin-6, as a representative marker of inflammation, correlated with MRP8/14, whereas ionized calcium and zinc did not. Our data suggest that infection and inflammation are not equal stimuli for MRP 8/14. The neutrophil appears to be the main source of MRP8/14 in this model.

Topics: Abscess; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Calcium; Calgranulin A; Calgranulin B; Cations, Divalent; Chlorides; Disease Models, Animal; Exudates and Transudates; Fluoroquinolones; Immunoenzyme Techniques; Inflammation; Interleukin-6; Lactams; Leukocyte Count; Neutrophils; Rabbits; Rats; Rifampin; Staphylococcal Infections; Zinc

This study was undertaken to investigate the usefulness of spiramycin in treatment for brucellosis in an animal model.. Eighty-four Sprague-Dawley rats were infected by intraperitoneal injection of Brucella melitensis suspension. Seven days after inoculation, four rats were selected randomly, killed and spleen cultures and Brucella standard tube agglutination test were carried out. All four rats were found to be infected. Eighty adult rats were randomly divided into four groups of 20 rats each. Tap water was given to the first group. Rifampicin 50 mg/kg per day and doxycycline 40 mg/kg per day were given to the second group, spiramycin 50 mg/kg per day orally was given to the third group, and a combination of spiramycin and rifampicin at the same dose and period was given to the fourth group. Duration of therapy regimens in all groups was 21 days. The spleens of all 80 rats were removed aseptically, homogenized, and placed onto Brucella agar plates to determine if viable bacteria were present.. Bacterial growth occurred in all of the rats' spleens in the first group and in two rats' spleens in the spiramycin group. Mean colony forming unit (c.f.u.) values were at the highest in the first group. The effectivities of spiramycin and rifampicin-spiramycin were similar to rifampicin-doxycycline. There were no differences in the treatment results between the three groups that received combined rifampicin-doxycycline, rifampicin-spiramycin and only spiramycin (P>0.05).. The results show that spiramycin cures experimental rat brucellosis and may be an effective alternative in the therapy of human brucellosis.

Topics: Animals; Anti-Bacterial Agents; Brucellosis; Cell Count; Disease Models, Animal; Enzyme Inhibitors; Male; Random Allocation; Rats; Rifampin; Spiramycin; Stem Cells

Efficacy of a new fluoroquinolone, sitafloxacin (DU-6859a), against Mycobacterium ulcerans was evaluated in vivo using the mouse footpad system. The growth of M. ulcerans in mouse footpads was completely inhibited when mice were fed with sitafloxacin at a dose of 25 mg/kg body weight per day; on the other hand similar effects were observed with ofloxacin at a dose of 100 mg/kg body weight per day. In the presence of rifampin, the above dose of sitafloxacin could be reduced by 75% to achieve total inhibition, while, under similar circumstances, the dose of ofloxacin could be reduced by only 50%. Either used singly or in combination with rifampin, the effects of sitafloxacin were bactericidal. The results suggest that sitafloxacin should be evaluated as a chemotherapeutic agent against M. ulcerans infection.

Topics: Animals; Anti-Infective Agents; Antibiotics, Antitubercular; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Female; Fluoroquinolones; Foot; Mice; Mice, Inbred BALB C; Mycobacterium Infections, Nontuberculous; Mycobacterium ulcerans; Rifampin

Limited information exists on the pharmacokinetic (PK)-pharmacodynamic (PD) relationships of drugs against Mycobacterium tuberculosis. Our aim was to identify the PK-PD parameter that best describes the efficacy of rifampin on the basis of in vitro and PK properties. Consistent with 83.8% protein binding by equilibrium dialysis, the rifampin MIC for M. tuberculosis strain H37Rv rose from 0.1 in a serum-free system to 1.0 mg/ml when it was tested in the presence of 50% serum. In time-kill studies, rifampin exhibited area under the concentration-time curve (AUC)-dependent killing in vitro, with maximal killing seen on all days and with the potency increasing steadily over a 9-day exposure period. MIC and time-kill studies performed with intracellular organisms in a macrophage monolayer model yielded similar results. By use of a murine aerosol infection model with dose ranging and dose fractionation over 6 days, the PD parameter that best correlated with a reduction in bacterial counts was found to be AUC/MIC (r(2) = 0.95), whereas the maximum concentration in serum/MIC (r(2) = 0.86) and the time that the concentration remained above the MIC (r(2) = 0.44) showed lesser degrees of correlation.

Topics: Aerosols; Animals; Antibiotics, Antitubercular; Cell Line; Disease Models, Animal; Dose-Response Relationship, Drug; Female; In Vitro Techniques; Macrophages; Male; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Rifampin; Tuberculosis, Pulmonary

Bacteria that adhere to implanted medical devices play an important role in industry and in modern medicine. Staphylococci are among the most common pathogens that cause biomaterial infections. Vascular prosthetic graft infection is one of the most feared complications that the vascular surgeon treats, frequently resulting in prolonged hospitalization, organ failure, amputation, and death. A rat model was used to investigate the topical efficacies of temporin A and the quorum-sensing inhibitor RNAIII-inhibiting protein (RIP) as prophylactic agents of vascular prosthetic graft infections caused by Staphylococcus aureus and Staphylococcus epidermidis with intermediate resistance to glycopeptides.. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses 1 cm2 followed by topical inoculation with 2x10(7) colony-forming units of bacterial strains. The study included, for each staphylococcal strain, a control group (no graft contamination), a contaminated group that did not receive antibiotic prophylaxis, and 6 contaminated groups that received grafts soaked with temporin A, RIP, rifampin, temporin A plus RIP, RIP plus rifampin, or temporin A plus RIP. The infection was evaluated by quantitative agar culture. When tested alone, temporin A and RIP showed comparable efficacies, and their efficacies were significantly higher than that of rifampin against both strains. All combinations showed efficacies significantly higher than that of each single compound. The combinations of temporin A and RIP exerted the strongest antistaphylococcal efficacies, eliminating infection by 100%.. The results of the present study make these molecules potentially useful for antimicrobial chemoprophylaxis in vascular surgery.

Topics: Administration, Topical; Animals; Anti-Bacterial Agents; Antimicrobial Cationic Peptides; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Resistance, Microbial; Drug Therapy, Combination; Glycopeptides; Implants, Experimental; Male; Microbial Sensitivity Tests; Oligopeptides; Polyethylene Terephthalates; Proteins; Rats; Rats, Wistar; Rifampin; Staphylococcal Skin Infections; Staphylococcus aureus; Staphylococcus epidermidis; Subcutaneous Tissue; Treatment Outcome; Vancomycin; Vancomycin Resistance

We have developed a rapid, continuous method for monitoring the effectiveness of several antibacterial agents in real time, noninvasively, by using a recently described mouse model of chronic biofilm infection (J. L. Kadurugamuwa et al., Infect. Immun. 71:882-890, 2003), which relies on biophotonic imaging of bioluminescent bacteria. To facilitate real-time monitoring of infection, we used a Staphylococcus aureus isolate that was made bioluminescent by inserting a modified lux operon into the bacterial chromosome. This bioluminescent reporter bacterium was used to study the antimicrobial effects of several antibiotics belonging to different molecular families. Treatment with rifampin, tobramycin, and ciprofloxacin was started 7 days after subcutaneous implantation of catheters precolonized with 10(4) CFU of S. aureus. Three different doses of antibiotics were administered twice a day for 4 consecutive days. The number of metabolically active bacteria in untreated mice and the tobramycin- and ciprofloxacin-treated groups remained relatively unchanged over the 4-week observation period, indicating poor efficacies for tobramycin and ciprofloxacin. A rapid dose-dependent decline in metabolic activity in rifampin-treated groups was observed, with almost a 90% reduction after two doses and nearly undetectable levels after three doses. The disappearance of light emission correlated with colony counts. After the final treatment, cell numbers rebounded as a function of concentration in a time-dependent manner. The staphylococci isolated from the catheters of mice treated with rifampin were uniformly resistant to rifampin but retained their in vitro susceptibilities to tobramycin and ciprofloxacin. Since the metabolic activities of viable cells and a postantibiotic effect could be detected directly on the support matrix nondestructively and noninvasively, the methodology is specifically appealing for investigating the effects of antibiotics on biofilms in vivo. Moreover, our study points to the possible use of biophotonic imaging for the detection of the development of resistance to therapeutic agents during treatment of chronic infections in vivo.

Topics: Animals; Anti-Bacterial Agents; Bacterial Infections; Biofilms; Catheterization; Ciprofloxacin; Colony Count, Microbial; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Monitoring; Luminescent Measurements; Mice; Rifampin; Staphylococcus aureus; Tobramycin

The increasing incidence of ciprofloxacin resistance in Streptococcus pneumoniae may limit the efficacy of the new quinolones in difficult-to-treat infections such as meningitis. The aim of the present study was to determine the efficacy of clinafloxacin alone and in combination with teicoplanin and rifampin in the therapy of ciprofloxacin-susceptible and ciprofloxacin-resistant pneumococcal meningitis in rabbits. When used against a penicillin-resistant ciprofloxacin-susceptible strain (Clinafloxacin MIC 0.12 microg/ml), clinafloxacin at a dose of 20 mg/kg per day b.i.d. decreased bacterial concentration by -5.10 log cfu/ml at 24 hr. Combinations did not improve activity. The same clinafloxacin schedule against a penicillin- and ciprofloxacin-resistant strain (Clinafloxacin MIC 0.5 microg/ml) was totally ineffective. Our data suggest that a moderate decrease in quinolone susceptibility, as indicated by the detection of any degree of ciprofloxacin resistance, may render these antibiotics unsuitable for the management of pneumococcal meningitis.

Topics: Animals; Cerebrospinal Fluid; Ciprofloxacin; Disease Models, Animal; Drug Resistance, Bacterial; Drug Therapy, Combination; Female; Fluoroquinolones; Meningitis, Pneumococcal; Microbial Sensitivity Tests; Rabbits; Rifampin; Streptococcus pneumoniae; Teicoplanin; Treatment Outcome

To identify the most active curative treatment of Buruli ulcer, two regimens incorporating the use of rifampin (RIF) were compared with the use of RIF alone in a mouse footpad model of Mycobacterium ulcerans infection. Treatments began after footpad swelling from infection and continued for 12 weeks with five doses weekly of one of the following regimens: (i) 10 mg of RIF/kg alone; (ii) 10 mg of RIF/kg and 100 mg of amikacin (AMK)/kg; and (iii) 10 mg of RIF/kg, 100 mg of clarithromycin (CLR)/kg, and 50 mg of sparfloxacin (SPX)/kg. The activity of each regimen was assessed in terms of the reduction of the average lesion index and acid-fast bacillus (AFB) and CFU counts. All three regimens displayed various degrees of bactericidal activity against M. ulcerans. The ranking of bactericidal activity was found to be as follows: RIF-AMK > RIF-CLR-SPX > RIF. RIF-AMK was able to cure M. ulcerans-infected mice and prevent relapse 26 weeks after completion of treatment. To determine the impact of different rhythms of administration of RIF-AMK on the suppression of M.ulcerans growth, mice were given the RIF-AMK combination for 4 weeks but doses were administered either 5 days a week or twice or once weekly. After completion of treatment, the mice were kept under supervision for 30 additional weeks. M. ulcerans was considered to have grown in the footpad if swelling was visually observed and harvests contained more than 5 x 10(5) AFB per footpad. The proportion of mice in which growth of M. ulcerans occurred, irrespective of drug dosage, was compared with the control mice to determine the proportion of M. ulcerans killed. Each dosage of RIF-AMK was bactericidal for M. ulcerans (P < 0.001), but the effect was significantly stronger in mice treated 5 days per week. The promising results of RIF-AMK treatment in M. ulcerans-infected mice support the clinical trial that is currently in progress under World Health Organization auspices in Ghana.

Topics: Amikacin; Animals; Anti-Bacterial Agents; Clarithromycin; Colony Count, Microbial; Disease Models, Animal; Drug Therapy, Combination; Female; Fluoroquinolones; Foot; Mice; Mice, Inbred BALB C; Mycobacterium Infections, Nontuberculous; Mycobacterium ulcerans; Rifampin; Skin Ulcer

Molecular detection of rifampin resistance (rpoB analysis) in Mycobacterium leprae was determined for 49 patients who experienced relapse of multibacillary leprosy and for 34 untreated patients. Molecular detection of ofloxacin resistance (gyrA analysis) was determined for the 12 patients who experienced relapse and who had received ofloxacin. Results of molecular tests were compared with the reference susceptibility test in the mouse footpad. Overall, the efficiency of molecular detection--that is, positive DNA amplification--was 95%, whereas that of the in vivo test was 55% (P<.001). Results of molecular detection and in vivo test were fully concordant when both were available--that is, for 35 rifampin--sensitive cases of leprosy (no rpoB mutation), 4 ofloxacin-sensitive cases (no gyrA mutation), 11 rifampin-resistant cases (rpoB missense mutations), and 1 ofloxacin-resistant case (gyrA mutation). rpoB and gyrA analysis appears to be an effective method for detection of rifampin and ofloxacin resistance in patients with leprosy.

Topics: Adult; Aged; Antibiotics, Antitubercular; Disease Models, Animal; DNA Gyrase; DNA-Directed RNA Polymerases; DNA, Bacterial; Drug Resistance, Bacterial; Humans; Leprosy; Microbial Sensitivity Tests; Middle Aged; Mutation; Mycobacterium leprae; Ofloxacin; Plant Proteins; Recurrence; Rifampin

to determine if local, in addition to systemic antibiotic prophylaxis (compared to that provided by systemic prophylaxis alone) provides additional benefit in terms of reducing graft infection.. gelatin-sealed Dacron grafts were interposed in the infrarenal aorta of 36 mongrels and inoculated with 1 ml of a S. aureus suspension. Group 1 (control group) received no prophylaxis and were inoculated with 1 ml containing 10(9)cfu/ml. Group 2 (n=6) received systemic prophylaxis (1 g cephamandole) and were inoculated with 10(5) cfu/ml (n=3) or 10(7) cfu/ml (n=3). Group 3 received systemic prophylaxis (1 g cephamandole) and were inoculated with 109 cfu/ml. Group 4 received systemic prophylaxis (2 g cephamandole) and were inoculated with 10(9)cfu/ml. In group 5 and 6 grafts were soaked in a rifampicin solution before use and inoculated with 10(9) cfu/ml. Group 5 received no systemic prophylaxis and group 6 received systemic prophylaxis (1 g cephamandole). Grafts were harvested at 2 weeks, and peritonitis, perigraft abscess, anastomotic disruption and graft occlusion recorded. Swabs were taken of the graft, the perigraft tissues and the peritoneal fluid. Graft segments were incubated in broth medium.. inoculation with 10(9) cfu/ml ensured graft infection. Systemic or local prophylaxis alone failed to prevent graft infection. Only systemic and local antibiotic prophylaxis provided significant better results than no prophylaxis at all (p<0.01) and local prophylaxis alone (p<0.05). However, total "graft sterility" was not achieved as bacteriologic analysis of the graft segments showed low bacterial counts (<10 bacteria/graft) in 5 of 6 grafts.. local and systemic prophylaxis provided more protection as demonstrated by the significant decrease in the incidence of "overt" graft infection. Total "graft sterility" cannot be expected in the case of an overwhelming bacterial challenge.

Topics: Animals; Antibiotic Prophylaxis; Aortic Valve; Autopsy; Disease Models, Animal; Dogs; Heart Valve Prosthesis; Models, Cardiovascular; Polyethylene Terephthalates; Prosthesis-Related Infections; Rifampin; Staphylococcal Infections

The object of the study was to assess the efficacy of rifampicin and the combination of rifampicin plus vancomycin in a rabbit model of experimental penicillin-resistant pneumococcal meningitis. We also studied the effect of concomitant dexamethasone on the CSF antibiotic levels and inflammatory parameters. The rabbit model of pneumococcal meningitis was used. Groups of eight rabbits were inoculated with 106 cfu/mL of a cephalosporin-resistant pneumococcal strain (MIC of cefotaxime/ceftriaxone 2 mg/L). Eighteen hours later they were treated with rifampicin 15 mg/kg/day, vancomycin 30 mg/kg/day or both plus minus dexamethasone (0.25 mg/kg/day) for 48 h. Serial CSF samples were withdrawn to carry out bacterial counts, antibiotic concentration and inflammatory parameters. Rifampicin and vancomycin promoted a reduction of >3 log cfu/mL at 6 and 24 h, and cfu were below the level of detection at 48 h. Combination therapy with vancomycin plus rifampicin was not synergic but it had similar efficacy to either antibiotic alone and it was able to reduce bacterial concentration below the level of detection at 48 h. Concomitant use of dexamethasone decreased vancomycin levels when it was used alone (P< 0.05), but not when it was used in combination with rifampicin. Rifampicin alone at 15 mg/kg/day produced a rapid bactericidal effect in this model of penicillin-resistant pneumococcal meningitis. The combination of vancomycin and rifampicin, although not synergic, proved to be equally effective. Using this combination in the clinical setting may allow rifampicin administration without emergence of resistance, and possibly concomitant dexamethasone administration without significant interference with CSF vancomycin levels.

Topics: Animals; Brain Edema; Cerebrospinal Fluid; Colony Count, Microbial; Dexamethasone; Disease Models, Animal; Drug Therapy, Combination; Female; Meningitis, Pneumococcal; Penicillin Resistance; Rabbits; Rifampin; Streptococcus pneumoniae; Time Factors; Vancomycin

Xanthorrizol (1) and 4-(1',5'-dimethylhex-4'-enyl)-2-methylphenol (2) were identified as the principal antimicrobial components of a CH(2)Cl(2)-MeOH (1:1) extract derived from Iostephane heterophylla. Compound 2 is a new natural product, but has been synthesized. Both compounds exhibited low level activity (MICs of 16-32 microg/mL) against methicillin-resistant staphylococci and vancomycin-resistant enterococci. They were either inactive or poorly active against Gram-negative bacteria and yeast. Mechanistic studies performed in Escherichia coli imp suggested nonspecific inhibition of DNA, RNA, and protein synthesis by both of these compounds. Compound 1 was tested in an in vivo model; it did not provide protection to mice infected with Staphylococcus aureus.

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Antifungal Agents; Asteraceae; Candida albicans; Disease Models, Animal; DNA; Drug Resistance, Microbial; Enterococcus faecium; Escherichia coli; Female; Magnetic Resonance Spectroscopy; Mexico; Mice; Mice, Inbred Strains; Microbial Sensitivity Tests; Phenols; Plant Roots; Plants, Medicinal; Protein Biosynthesis; Proteins; RNA; Spectrophotometry, Ultraviolet; Staphylococcus aureus; Vancomycin

Strategies to improve patient compliance in tuberculosis chemotherapy include the use of sustained release drug delivery systems. In this study, Poly (DL-lactide-co-glycolide) (PLG) microparticles containing a combination of isoniazid and rifampicin were developed as sustained release carrier systems. A single dose of PLG microparticles exhibited a sustained release of isoniazid and rifampicin in vivo up to 7 and 6 weeks, respectively. Free drugs (in combination) injected in the same doses were detectable in vivo up to 24 h only. One dose of PLG microparticles cleared bacteria more effectively from lungs and liver in an experimental murine model of tuberculosis after low-dose PLG combination drug therapy and in liver after high-dose PLG combination drug therapy as compared with a daily administration of the free drugs. These results suggest that PLG microparticles offer an improvement for tuberculosis chemotherapy over the conventional treatment.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Capsules; Disease Models, Animal; Drug Carriers; Drug Delivery Systems; Drug Therapy, Combination; Female; Isoniazid; Lactic Acid; Male; Mice; Mycobacterium tuberculosis; Particle Size; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Polymers; Rifampin; Treatment Outcome; Tuberculosis

In situ prosthetic graft replacement (ISPGR) of an infected prosthesis raises the risk of recurrent infection in the new graft, especially in cases involving drug-resistant microorganisms. The purpose of this animal study was to evaluate in situ replacement of a vascular graft infected by a highly rifampin-resistant strain of Staphylococcus epidermidis with the use of a rifampin-bonded polyester graft. Antibiotic bonding was obtained by soaking grafts in a high dose of rifampin solution (60 mg/mL). The infrarenal abdominal aorta of 20 dogs was replaced using a polyester prosthesis infected with a highly rifampin-resistant strain of Staphylococcus epidermidis. One week later, the 18 surviving animals were randomized into three groups. Group I (n = 6) did not undergo reoperation. Group II (n = 6) underwent ISPGR using a rifampin-bonded prosthesis. Group III (n = 6) underwent ISPGR using an untreated prosthesis. All surviving animals were killed 28 days after the first procedure. Infectious signs were noted and bacteriological study was carried out on explanted prostheses and various tissue samples. The findings of this experimental study show that soaking a polyester prosthesis in a high-dose rifampin solution can prevent reinfection after in situ replacement of a prosthesis infected by a highly rifampin-resistant Staphylococcus epidermidis.

Topics: Anastomosis, Surgical; Animals; Antibiotics, Antitubercular; Disease Models, Animal; Dogs; Female; Polyesters; Prosthesis Implantation; Random Allocation; Rifampin; Staphylococcal Infections; Staphylococcus epidermidis; Surgical Wound Infection; Survival Analysis; Time Factors; Treatment Outcome; Vascular Surgical Procedures

A Mycobacterium tuberculosis (H37Rv)-infected guinea pig model was used to screen for targeted delivery to the lungs by insufflation (with lactose excipient) or nebulization, of either rifampicin alone, rifampicin within poly(lactide-co-glycolide) microspheres (R-PLGA) or polymer microparticles alone (PLGA). Animals treated with single and double doses of R-PLGA microspheres exhibited significantly reduced numbers of viable bacteria, inflammation and lung damage compared with lactose-, PLGA- or rifampicin-treated animals 28 days post-infection (P < 0.05). Two doses of R-PLGA resulted in reduced splenic enlargement. These studies support the potential of R-PLGA delivered to the lung to treat pulmonary tuberculosis.

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Drug Delivery Systems; Guinea Pigs; Insufflation; Male; Nebulizers and Vaporizers; Particle Size; Rifampin; Tuberculosis

The newer rifamycin, rifalazil (RLZ) (previously known as KRM-1648), has been shown in prior experiments to be a highly potent drug against Mycobacterium tuberculosis. In this report, we studied the efficacy of RLZ in combination with pyrazinamide (PZA) and ethambutol (EMB) in a long-term in vivo experiment and compared their activity with the isoniazid (INH)-rifampin (RIF) combination which is presently used in the clinic. Combinations of RLZ with PZA alone or with both PZA and EMB were both found to have sterilizing activities comparable to that of the INH-RIF combination but significantly better activity with respect to relapse of infection. These results suggest that RLZ, or other agents with similar activity, could be combined with available agents to act as a potential alternative drug regimen to the currently used INH-RIF combination.

Topics: Animals; Antitubercular Agents; Colony-Forming Units Assay; Disease Models, Animal; Drug Therapy, Combination; Ethambutol; Female; Isoniazid; Mice; Pyrazinamide; Rifampin; Rifamycins; Tuberculosis

Mycobacterium tuberculosis can persist in an altered physiological state for many years after initial infection, and it may reactivate to cause active disease. An analogous persistent state, possibly consisting of several different subpopulations of bacteria, may arise during chemotherapy; this state is thought to be responsible for the prolonged period required for effective chemotherapy. Using two models of drug-induced persistence, we show that both microaerophilic stationary-phase M. tuberculosis treated with a high dose of rifampin in vitro and pyrazinamide-induced persistent bacteria in mice are nonculturable yet still contain 16S rRNA and mRNA transcripts. Also, the in vitro persistent, plate culture-negative bacteria incorporate radioactive uridine into their RNA in the presence of rifampin and can rapidly up-regulate gene transcription after the replacement of the drug with fresh medium and in response to heat shock. Our results show that persistent M. tuberculosis has transcriptional activity. This finding provides a molecular basis for the rational design of drugs targeted at persistent bacteria.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Disease Models, Animal; Drug Resistance, Microbial; Mice; Mice, Inbred BALB C; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; RNA, Bacterial; RNA, Messenger; RNA, Ribosomal, 16S; Time Factors; Transcription, Genetic; Tuberculosis

Topics: Animals; Brucella melitensis; Brucellosis; Disease Models, Animal; Erythromycin; Male; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Rifampin; Treatment Outcome

To further the development of a multidrug regimen for treatment of leprosy that is suitable for monthly administration and fully supervisable, the bactericidal activities against Mycobacterium leprae of HMR 3647 (HMR), moxifloxacin (MXFX) and rifapentine (RPT) were measured by the proportional bactericide technique in the mouse footpad system, and compared with those of the established antileprosy drugs clarithromycin (CLARI), ofloxacin (OFLO) and rifampicin (RMP). Administered in five daily doses of 100 mg per kg body weight, HMR appeared slightly more bactericidal than CLARI, but the difference did not attain statistical significance. Administered as single doses, MXFX in a dosage of 150 mg per kg was more active than OFLO in the same dosage, and displayed the same level of activity as RMP in a dosage of 10 mg per kg; the combination MXFX-minocycline (MINO) (MM) was more bactericidal than the combination OFLO-MINO (OM); RPT in a dosage of 10 mg per kg was more bactericidal than RMP administered in the same dosage, and even more active than the combination RMP-OFLO-MINO (ROM); the combination RPT-MXFX-MINO (PMM) killed 99.9% of viable M. leprae, and was slightly more bactericidal than was RPT alone, indicating that the combination PMM showed an additive effect against M. leprae. These promising results justify a clinical trial among lepromatous patients, in which MM is being compared with OM, and PMM with ROM, in terms of efficacy and tolerance.

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Aza Compounds; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Female; Fluoroquinolones; Leprostatic Agents; Leprosy; Mice; Mice, Inbred Strains; Minocycline; Moxifloxacin; Probability; Quinolines; Rifampin; Treatment Outcome

A rabbit model for Staphylococcus aureus osteomyelitis was used to compare 28-day combination antibiotic therapy using oral rifampin (40 mg/kg, twice daily) plus oral azithromycin (50 mg/kg, once per day), oral clarithromycin (80 mg/kg, twice daily), or parenteral nafcillin (30 mg/kg, four times daily). The left tibial metaphysis of New Zealand White rabbits was infected with Staphylococcus aureus. Grades 3 to 4 osteomyelitis (according to the Cierny-Mader classification system) development in the rabbits was confirmed radiographically. After antibiotic therapy regimens of 28 days, all tibias from controls that were infected but left untreated (n = 10) revealed positive cultures for Staphylococcus aureus at a mean concentration of 2.8 x 10(4) colony forming units/g bone. The rifampin plus clarithromycin (n = 15) and rifampin plus azithromycin (n = 15) groups showed significantly lower percentages of positive Staphylococcus aureus infection (20% and 13.3%, respectively) and bacterial concentrations (3.5 x 10(1) and 1.75 x 10(1) colony forming units/g bone, respectively). The osteomyelitic tibias of the nafcillin plus rifampin treated group (n = 7) showed no detectable Staphylococcus aureus infection (significantly lower than controls). The differences observed for bone bacterial concentrations and sterilization percentages between the antibiotic treated groups were not statistically significant. Although fluoroquinolones (including ofloxacin and ciprofloxacin) are the agents usually prescribed with rifampin, increasing resistance has been observed. Although macrolides traditionally are not used in the treatment of osteomyelitis, the results of this study indicate that azithromycin and clarithromycin may be attractive partners for rifampin for the treatment of Staphylococcus aureus osteomyelitis in humans.

Topics: Administration, Oral; Animals; Anti-Bacterial Agents; Azithromycin; Biological Availability; Clarithromycin; Colony Count, Microbial; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Nafcillin; Osteomyelitis; Rabbits; Rifampin; Staphylococcal Infections; Tibia; Treatment Outcome

Rifapentine is a long-acting rifamycin which may be useful for intermittent drug therapy against tuberculosis. In this study we measured the efficacies of rifapentine-containing intermittent drug regimens for preventive therapy using the Cornell mouse model of latent tuberculosis. We infected groups of mice intravenously with Mycobacterium tuberculosis and then treated them with isoniazid and pyrazinamide for 12 weeks according to the Cornell latency development protocol. After a 4-week interval of no treatment, experimental preventive therapy was administered by esophageal gavage for 12 or 18 weeks. After equilibration and dexamethasone amplification treatment, mouse organs were analyzed by quantitative colony counts to measure the effectiveness of therapy. Our results showed that once-weekly isoniazid plus rifapentine combination therapy for 18 weeks was an effective preventive regimen with sterilizing potency and bacillary load reduction comparable to those of daily isoniazid therapy for 18 weeks. Monotherapy with rifapentine weekly or fortnightly or with rifampin twice weekly for up to 18 weeks did not offer advantages in reducing bacillary load or in sterilizing organs compared to the effects of a placebo. These results with the Cornell mouse model indicate that once-weekly, short-course preventive therapy with isoniazid plus rifapentine is effective and may warrant investigation in humans with latent tuberculosis infection.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Colony Count, Microbial; Disease Models, Animal; Drug Therapy, Combination; Female; Isoniazid; Mice; Mycobacterium tuberculosis; Rifampin; Stem Cells; Tuberculosis

Besides direct bactericidal activity, long-term effectiveness is one of the most important features to consider when developing new drugs for chemotherapy. In this study, we evaluated the ability of rifapentine (RFP), in monotherapy and combination therapy, to completely eradicate a Mycobacterium tuberculosis infection and to prevent relapse posttreatment in a Swiss mouse model. The combination of RFP, isoniazid (INH), and pyrazinamide (PZA) administered daily resulted in an apparent clearance of M. tuberculosis organisms in the lungs and spleens of infected mice after 10 weeks of treatment. However, 3 months after the cessation of therapy, bacterial regrowth occurred in mice treated for a 12-week period, indicating a relapse of infection. In intermittent treatment regimens of RFP in combination with INH and PZA, sterilization was achieved when mice were treated two to five times per week for 9 weeks. Bacterial growth was still observed in the once-weekly treatment group. Our results show that mouse models can predict important parameters for new drugs. We stress the necessity for long-term posttreatment observation in animal models for the routine evaluation of new drugs for antituberculosis chemotherapy.

Topics: Animals; Antibiotics, Antitubercular; Antitubercular Agents; Disease Models, Animal; Drug Therapy, Combination; Evaluation Studies as Topic; Female; Isoniazid; Mice; Mycobacterium tuberculosis; Pyrazinamide; Rifampin; Rifamycins; Tuberculosis

A subcutaneous catheter model in the rat was developed that allowed the study of prevention and treatment strategies for foreign body infection. In contrast to earlier models, the foreign body was inoculated with a low inoculum of Staphylococcus epidermidis just before implantation, thus mimicking intraoperative contamination with skin flora. Reproducible infection of all catheters followed if no prophylaxis was given. However, foreign body infection could be prevented or treated with antibiotics such as teicoplanin, which was marginally effective, and rifampicin, which proved very effective.

Topics: Animals; Anti-Bacterial Agents; Antibiotic Prophylaxis; Catheters, Indwelling; Disease Models, Animal; Foreign Bodies; Prosthesis-Related Infections; Rats; Rats, Inbred F344; Rats, Wistar; Rifampin; Staphylococcal Infections; Staphylococcus epidermidis; Teicoplanin

Tuberculous meningitis (TBM) is a devastating form of tuberculosis that occurs predominantly in children and in immunocompromised adults. To study the pathogenesis of TBM, a rabbit model of acute mycobacterial central nervous system infection was set up (8-day study). Inoculation of live Mycobacterium bovis Ravenel intracisternally induced leukocytosis (predominantly mononuclear cells), high protein levels, and release of tumor necrosis factor-alpha (TNF-alpha) into the cerebrospinal fluid within 1 day. Histologically, severe meningitis with thickening of the leptomeninges, prominent vasculitis, and encephalitis was apparent, and mortality was 75% by day 8. In animals treated with antituberculous antibiotics only, the inflammation and lesions of the brain persisted despite a decrease in mycobacteria; 50% of the rabbits died. When thalidomide treatment was combined with antibiotics, there was a marked reduction in TNF-alpha levels, leukocytosis, and brain pathology. With this combination treatment, 100% of the infected rabbits survived, suggesting a potential clinical use for thalidomide in TBM.

Topics: Animals; Antibiotics, Antitubercular; Disease Models, Animal; Drug Therapy, Combination; Immunosuppressive Agents; Isoniazid; Mycobacterium bovis; Rabbits; Rifampin; Thalidomide; Tuberculosis, Meningeal

The efficacy of various group antibacterial drugs: aminoglycosides, quinolones, 3rd generation cephalosporins, doxycycline, rifampicin, ampicillin and azthreonam was estimated in the treatment of experimental plague of albino mice induced by antigen complete and atypical strains of the F1- phenotype plague microbe. The in vitro experiments showed that all the strains of the plague microbe irrespective of the phenotype (F1+ or F1-) were highly susceptible to the drugs. The animal experiments demonstrated that aminoglycosides (streptomycin, kanamycin, tobramycin, gentamicin and amikacin) and cephalosporins (ceftriaxone and ceftazidim) were highly efficient in the prophylaxis and treatment of plague due to F1+ and F1- strains. In experimental plague due to F1- phenotype plague microbe the prophylactic effects of cefotaxime, cefoperazone, sulbactam/ampicillin, azthreonam, ciprofloxacin and rifampicin were lower. However, increase of the daily doses of the drugs and prolongation of the treatment course up to 7 days made it possible to increase the protective effects up to 80-100 per cent. Doxycycline and ampicillin were not sufficiently efficient even when used for 10 days in the prophylaxis of plague due to F1- strains.

Topics: Aminoglycosides; Ampicillin; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Antibiotics, Antitubercular; Antigens, Bacterial; Aztreonam; Bacterial Proteins; Cephalosporins; Disease Models, Animal; Doxycycline; Fluoroquinolones; Mice; Monobactams; Penicillins; Phenotype; Plague; Rifampin

The anticoagulant and antithrombotic effects of YM-75466 (N-[4-[(1-acetimidoyl-4-piperidyl)oxy]phenyl]-N-[(7-amidino-2-naph thyl)methyl]sulfamoyl acetic acid monomethanesulfonate), a novel orally-active factor Xa (FXa) inhibitor, and warfarin were compared in mice. Both agents were orally administered in all studies. In ex vivo studies, the peak effects of YM-75466 occurred 1 hr after administration while the peak of warfarin activity occurred 18 hr after administration. At each peak, both YM-75466 and warfarin prolonged coagulation time dose-dependently. The dose response curve of warfarin for prothrombin time was steeper than that of YM-75466. In a thromboplastin-induced thromboembolism model, administration of 30 mg/kg YM-75466 or 3 mg/kg warfarin significantly improved the lethality ratio. In blood loss studies, YM-75466 did not increase blood loss from the tail even at 30 mg/kg, while warfarin markedly increased blood loss at 3 mg/kg. Agents that interfere with warfarin action did not interfere with YM-75466 action. In conclusion, this study shows that YM-75466 has advantages over warfarin: i) rapid onset of anticoagulant activity, ii) wide therapeutic range, iii) little effect on bleeding and iv) lack of drug interaction with agents that interfere with warfarin. These results suggest that YM-75466 may be promising as a novel oral anticoagulant agent.

Topics: Administration, Oral; Analgesics, Non-Narcotic; Animals; Anti-Bacterial Agents; Anticoagulants; Anticonvulsants; Antifibrinolytic Agents; Blood Coagulation; Carbamazepine; Cimetidine; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Erythromycin; Factor Xa Inhibitors; Fibrinolytic Agents; Hemorrhage; Male; Mice; Mice, Inbred ICR; Partial Thromboplastin Time; Phenytoin; Piperidines; Prothrombin Time; Rifampin; Sulfonamides; Thromboembolism; Thromboplastin; Vitamin K 1; Warfarin

Antimicrobial coating of medical devices has recently emerged as a potentially effective method for preventing device-related infections. The objective of this animal study was to examine in vivo the antimicrobial efficacy of prosthetic heart valve sewing ring fabric coated with: (i) silver; (ii) combined minocycline and rifampin (M/R); or (iii) combined chlorhexidine and chloroxylenol (CH/CX).. A rabbit model of Staphylococcus aureus colonization and infection of subcutaneously implanted fabric of prosthetic heart valve sewing rings was used. Following administration of anesthesia and preoperative antibiotic prophylaxis, 0.5 x 0.5 cm samples of fabric were placed subcutaneously into the back of rabbits. Each rabbit received a total of eight samples: (i) two uncoated; (ii) two silver-coated; (iii) two M/R-coated; and (iv) two CH/CX-coated. After injecting a bacterial inoculum of 2 x 10(5) c.f.u. of S. aureus onto each implanted sample, the wounds were sutured. Rabbits were monitored daily for one week, killed and the test fabrics removed and cultured.. Rates of device colonization, device-related infection and device-related abscess were similar between the uncoated and silver-coated devices. Devices coated with M/R were less likely to be colonized or cause device-related infection when compared with uncoated devices, and less likely to be associated with abscess formation than silver-coated devices. There was a tendency for CH/CX-coated devices to be less colonized than uncoated devices. Only M/R-coated and CH/CX-coated devices produced zones of inhibition in vitro. Implantation of M/R-coated and CH/CX-coated devices in rabbits did not result in detectable systemic concentrations of the antimicrobial coating agents. Colonization of antimicrobial-coated devices was not associated with resistant S. aureus isolates.. These results suggest that silver-coated sewing rings may not prove to be clinically anti-infective. In contrast, antimicrobial-coated sewing rings that produce effective zones of inhibition, particularly those coated with M/R, are likely to be clinically protective.

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents, Local; Antibiotic Prophylaxis; Bacterial Adhesion; Chlorhexidine; Coated Materials, Biocompatible; Colony Count, Microbial; Disease Models, Animal; Drug Combinations; Female; Heart Valve Prosthesis; Minocycline; Prosthesis Design; Prosthesis-Related Infections; Rabbits; Rifampin; Silver Sulfadiazine; Staphylococcal Infections

The purpose of the present study was to evaluate the combination of azithromycin and rifampicin on experimental chronic osteomyelitis due to Staphylococcus aureus. Alterations in bone bacterial titre, activity of tumour necrosis factor (TNF), a cytokine implicated in inflammation-induced bone pathology, and histopathological changes during infection and following antibiotic treatment were evaluated. Rats were infected with S. aureus by direct tibial inoculation and then randomized 56 days after infection to receive saline treatment or a combination of azithromycin and rifampicin (50 mg/kg po and 25 mg/kg sc respectively) once daily for 21 days. The combination of azithromycin and rifampicin was successful as determined by dramatic reduction in bone bacterial counts (approximately log 4 cfu), but regrowth of the organisms occurred suggesting that the duration of treatment was insufficient. TNF alpha mRNA and TNF activity were constantly elevated by approximately 20- and >200-fold, respectively, and remained elevated irrespective of antimicrobial treatment. Bone histology revealed extensive increase in bone turnover in both the infected and antibiotic treated bones with no difference being observed between the groups. This suggests that, in infected bone, the elevated TNF levels observed may be directly related to the bone pathology and both remain largely unchanged despite potent antibiotic therapy.

Topics: Animals; Anti-Bacterial Agents; Antibiotics, Antitubercular; Azithromycin; Bone and Bones; Chronic Disease; Disease Models, Animal; Drug Therapy, Combination; Osteomyelitis; Rats; Rifampin; RNA, Messenger; Staphylococcus aureus; Tumor Necrosis Factor-alpha

For many years, Rifampicin has been used empirically for the treatment of hemophilic chronic synovitis with encouraging results. A study was performed in which Rifampicin was shown to reduce the inflammation of joints affected by hemophilic synovitis. A clinical study was performed on 48 hemophilic patients (48 joints). Seventeen elbows, eight knees, and 23 ankles were treated. The mean age of the patients was 6 years (range, 4-23 years) and the mean followup was 29 months (range, 24-53 months). Overall, 40 excellent results and eight good results were obtained. The average number of weekly injections of Rifampicin was 3.06 (range, 1-10 injections). Eight patients experienced pain on the first injection, which subsided gradually with the subsequent procedures. Synoviorthesis with Rifampicin seems to be a good method for the treatment of hemophilic synovitis, especially in small joints (elbows and ankles) and in younger children.

Topics: Adolescent; Adult; Age Factors; Animals; Ankle Joint; Anti-Bacterial Agents; Arthralgia; Child; Child, Preschool; Chronic Disease; Disease Models, Animal; Elbow Joint; Follow-Up Studies; Forecasting; Hemarthrosis; Hemophilia A; Hemophilia B; Humans; Injections, Intra-Articular; Knee Joint; Logistic Models; Male; Rabbits; Rifampin; Synovitis; Treatment Outcome

The objective of this study was to examine the effects of rifampin on itraconazole pharmacokinetics, at steady state, in three Yucatan miniature pigs. The pits received daily during three weeks oral itraconazole at a dosage of 200 mg at the beginning of the meal, then during the next two weeks oral itraconazole combined with an intravenous administration of rifampin at a dosage of 10 mg/kg/day. The coadministration of rifampin resulted in a 18 fold decrease of the Cmax of itraconazole [from 113.0 (SD: 17.2) to 6.2 ng/ml (SD: 3.9)], and in a 22 fold decrease of the AUC [from 1652.7 (SD: 297.7) to 75.6 ng.h/ml (SD: 30.01)]. The active metabolite of itraconazole, hydroxyitraconazole, was undetectable. This study demonstrates that rifampin considerably affects itraconazole kinetics at steady-state in this model of micropig, probably by inducing the hepatic metabolism of itraconazole.

Topics: Administration, Oral; Adult; Animals; Antibiotics, Antitubercular; Antifungal Agents; Catheterization, Peripheral; Disease Models, Animal; Drug Combinations; Female; Humans; Injections, Intravenous; Itraconazole; Rifampin; Swine

Autobacteriography was proposed as a bacteriological method to follow distribution and localization of bacteria in experimentally infected animals. Infectious organisms were restricted to rifampicin-resistant strains to prevent contamination during autobacteriography. Mice were infected with Staphylococcus aureus Smith diffuse type RFPr (rifampicin-resistant) by the intravenous route and frozen at various intervals after infection. Whole body sections (40-microns thick) of the mice were transferred onto selective agar medium containing rifampicin to incubate at 37 degrees C. On day 1 after infection, dense colonies of the infecting organism on the sections were distributed in the whole body. On day 3, few organisms were detected in the liver and many were observed in the spleen, kidney and intestinal tract. On days 7, 14 and 21, the organisms in the liver and spleen disappeared, and those in the kidney and intestine remained. The remaining infectious organisms were demonstrated in the kidney and intestinal tract by autobacteriography of mice infected with S. aureus Smith compact type RFPr. By cultivation of the homogenate of the gastrointestinal tissues and their contents, the infectious organisms were detected mainly in the lower small intestines, cecum and large intestines.

Topics: Animals; Bacterial Translocation; Bacteriological Techniques; Disease Models, Animal; Drug Resistance, Microbial; Intestines; Male; Mice; Mice, Inbred Strains; Rifampin; Staphylococcal Infections; Staphylococcus aureus

A modified rabbit meningitis model is described for determining the PAE in vivo, which utilised a self-standing device for repeatedly sampling pure CSF. The model allowed the PAEs of ciprofloxacin and rifampicin on Escherichia coli ATCC 25922 to be determined following PAE induction in vitro, or in vivo in CSF after intrathecal injection or during the last 1.5 h of a 7 h iv continuous infusion. The estimated volumes of distribution of ciprofloxacin and rifampicin in CSF were 0.68 +/- 0.24 mL and 0.74 +/- 0.04 mL, respectively, and the terminal elimination half lives were 1.8 +/- 0.5 h and 2.2 +/- 0.3 h, respectively. PAEs of approximately 2 h were obtained in vivo and in vitro after exposing E. coli to 3 x MIC of ciprofloxacin in vitro and to 1 x MIC of drug in vivo. When the organism was exposed to rapidly declining concentrations in vivo, only a minimal PAE was observed for both antibiotics. Moreover, a PAE of 3.1 +/- 1.3 h of rifampicin was obtained in vivo, being smaller than the 4.8 h PAE observed in vitro, which might be explained by the binding of 45 +/- 6.5% rifampicin to proteins in the CSF.

Topics: Animals; Anti-Infective Agents; Antibiotics, Antitubercular; Ciprofloxacin; Disease Models, Animal; Dose-Response Relationship, Drug; Escherichia coli; Female; Infusions, Intravenous; Injections, Spinal; Meningitis, Bacterial; Microbial Sensitivity Tests; Rabbits; Rifampin

Results of in vitro time-kill synergy studies using subinhibitory, inhibitory, or suprainhibitory concentrations of bactericidal agents were compared with treatment outcomes of experimental infective endocarditis due to a methicillin-susceptible strain of Staphylococcus aureus. For rifampin-cephalosporin combinations, in vitro synergy testing using recommended fractions of the MIC failed to predict antagonism in vivo while concentrations above the MIC corresponded with antagonism in vivo.

Topics: Animals; Cefazolin; Cefpirome; Cephalosporins; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Drug Therapy, Combination; Endocarditis, Bacterial; Gentamicins; Microbial Sensitivity Tests; Nafcillin; Predictive Value of Tests; Rabbits; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Time Factors

The dose-response activity of rifabutin and the comparative activities of rifabutin and rifapentine were evaluated in the beige mouse model of disseminated Mycobacterium avium complex (MAC) infection. In the dose-response study, mice were infected intravenously with approximately 10(7) viable M. avium ATCC 49601. Treatment with rifabutin at 10, 20, or 40 mg/kg of body weight was started 7 days postinfection and was administered daily for 10 days. The mice were sacrificed 3 to 5 days after the last dose. Spleens, livers, and lungs were homogenized, and viable cell counts were determined by serial dilution and plating onto Middlebrook 7H10 agar. A dose-related reduction in MAC cell counts in the organs was noted for this MAC isolate. The comparative activities of rifabutin and rifapentine were determined against a total of five MAC isolates in the beige mouse model. Rifabutin or rifapentine (20 mg/kg each) was administered to infected mice for 10 days. Groups of treated mice were compared with untreated control animals. Despite favorable in vitro susceptibility results, rifabutin and rifapentine had activities in the spleens against only two of the five MAC isolates. For these two MAC isolates, rifabutin was more active than rifapentine. These agents had activities in the lungs against three of five isolates. Further study of rifabutin or rifapentine against a broader range of clinical isolates in a murine infection model may be useful as part of the continuing development of newer rifamycins as anti-MAC agents.

Topics: Animals; Antitubercular Agents; Colony Count, Microbial; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Humans; Lung; Mice; Mice, Inbred C57BL; Mycobacterium avium; Mycobacterium avium Complex; Rifabutin; Rifampin; Tuberculosis

The presence of rifampicin (RFP) specific IgG in the sera of rabbits immunized with RFP or with two RFP-protein conjugates (RFP-bovine serum albumin, RFP-BSA and RFP-rabbit serum albumin RFP-RSA) was measured by ELISA. The way of conjugation and the molecular conjugation rate were different between RFP-BSA and RFP-RSA. The titre of RFP specific IgG was 1:10-1:100 in RFP immunized rabbits, 1:100-1:1,000 in RFP-RSA immunized rabbits, and over 1:1000 in RFP-BSA immunized rabbits. The binding properties of the sera to RFP were demonstrated by inhibition assay. These are the models of RFP sensitization first established by immunization animals with RFP itself or RFP-protein conjugates.

Topics: Animals; Disease Models, Animal; Drug Hypersensitivity; Enzyme-Linked Immunosorbent Assay; Immunoglobulin G; Male; Rabbits; Rifampin; Serum Albumin, Bovine

Infections of implanted devices are of increasing frequency and importance, representing a significant limitation of many therapeutic modalities. There are puzzling features of implant-associated infection including the changes in microbial flora, the tendency to chronicity and impaired responses to conservative modes of treatment. The concept of the bacterial biofilm as a shielding mechanism generated by bacteria adherent to artificial surfaces has recently been proposed as an explanation for these features. The biofilm is a term applied to a complex comprising the implant surface, adherent bacteria and a specialized matrix enclosing the bacteria. The matrix of the biofilm is an electrostatically charged glue-like extracellular polymer derived by bacterial enzymes acting on tissue carbohydrates, formed by bacteria when adherent to surfaces. This matrix binds the bacteria to the surface providing a sequestration affording selective protection against harmful elements of the environment, especially mechanisms of host defenses and antimicrobial agents. These biological systems are complex to study because of the dynamic interaction of the microbial variables, host defenses, properties of synthetic materials and the biofilm matrix itself. There is a need for a laboratory model in which the variables can be controlled permitting the researcher to examine the outcomes of modifying one variable at a time in a planned and orderly manner. The practical way to attain this end is the conduct of studies in a stable reproducible animal model of localized biofilm-implant infection. Staphylococcus epidermidis is a representative of the class of microorganisms predominant in implant-associated infection. This paper describes the development of a model utilizing an implant-S. epidermidis-biofilm infection localized to the peritoneal cavity of the mouse. The natural history of the infection has been well documented and is stable in all respects for periods exceeding 3 months. This chronicity is especially advantageous in analyzing the impact of long-term therapeutic modalities and necessary periods of recovery and assessment. A representative example of an experimental use of this model to determine the relative efficacy of antibiotic therapeutic regimes is described, demonstrating its scope and efficacy.

Topics: Animals; Catheterization; Catheters, Indwelling; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Female; Humans; Mice; Mice, Inbred C57BL; Peritoneal Cavity; Peritoneal Dialysis, Continuous Ambulatory; Prosthesis-Related Infections; Rifampin; Staphylococcal Infections; Staphylococcus epidermidis; Vancomycin

The most appropriate therapy for meningitis caused by Streptococcus pneumoniae strains resistant to the extended-spectrum cephalosporins is unknown. We evaluated ceftriaxone, vancomycin, and rifampin alone and in different combinations and meropenem, cefpirome, and clinafloxacin alone in the rabbit meningitis model. Meningitis was induced in rabbits by intracisternal inoculation of one of two pneumococcal strains isolated from infants with meningitis (ceftriaxone MICs, 4 and 1 microgram/ml, respectively). Two doses, 5 h apart, of each antibiotic were given intravenously (except that ceftriaxone was given as one dose). Cerebrospinal fluid bacterial concentrations were measured at 0, 5, 10, and 24 h after therapy was started. Clinafloxacin was the most active single agent against both strains. Against the more resistant strain, ceftriaxone or meropenem alone was ineffective. The combination of vancomycin and ceftriaxone was synergistic, suggesting that this combination might be effective for initial empiric therapy of pneumococcal meningitis until results of susceptibility studies are available.

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Cefpirome; Ceftriaxone; Cephalosporins; Disease Models, Animal; Drug Resistance, Microbial; Drug Synergism; Drug Therapy, Combination; Fluoroquinolones; Male; Meningitis, Pneumococcal; Meropenem; Microbial Sensitivity Tests; Penicillin Resistance; Quinolones; Rabbits; Rifampin; Thienamycins; Vancomycin

We compared ciprofloxacin, rifampin, and gentamicin treatments, alone and in combination, for 5 days in the therapy of experimental aortic valve endocarditis in rats caused by a clinical isolate of vancomycin-resistant Enterococcus faecium. The MICs and MBCs of vancomycin, ciprofloxacin, rifampin, and gentamicin were 250 and > 1,000, 3.1 and 6.3, 0.098 and 1.6, and 12.5 and > 50 micrograms/ml, respectively. Infected rats were sacrificed after completing 5 days of therapy. Additional rats within each treatment group were followed for 5 days beyond the last dose of antibiotic therapy. Although survivals in the different groups were not significantly different after 5 days of therapy, survival was significantly better 5 days beyond the last dose of antibiotic therapy in rats treated with rifampin-containing regimens. The combination of ciprofloxacin and gentamicin was bactericidal in vitro and in vegetations from rats with enterococcal endocarditis. Rifampin alone was similarly bactericidal in vivo, but it was not significantly better than rifampin in combination with other antibiotics. Subpopulations resistant to rifampin, but not ciprofloxacin, were detected in the inoculum and in most vegetations during therapy. However, the combination of ciprofloxacin plus both gentamicin and rifampin reduced both the rifampin-susceptible and -resistant population in vegetations of 9 of 10 animals below the level of detection after 5 days of therapy. Nevertheless, a residual enterococcal population apparently remained in numbers of < 2 log10 CFU/g after 5 days of therapy, which resulted in relapse. Perhaps a longer course of therapy would have eliminated this residual population and improved efficacy.

Topics: Ampicillin Resistance; Animals; Ciprofloxacin; Disease Models, Animal; Drug Resistance, Microbial; Drug Therapy, Combination; Endocarditis, Bacterial; Enterococcus faecalis; Gentamicins; Gram-Positive Bacterial Infections; Male; Microbial Sensitivity Tests; Rats; Rats, Sprague-Dawley; Rifampin; Vancomycin

The in vivo anti-Mycobacterium leprae activity of the newly synthesized benzoxazinorifamycin, KRM-1648, was studied. KRM-1648 was given orally to athymic nude mice, infected subcutaneously with M. leprae in the hindfoot pad, at doses between 0.001 and 0.01 mg of the drug/mouse/day six times per week, from day 31 to day 80. KRM-1648 administration markedly suppressed bacterial growth in the foot pads for 360 days. KRM-1648 given daily at the dose of 0.01 mg/mouse elicited a 2-4-log decrease in the number of acid-fast bacilli. The therapeutic effects of KRM-1648 were significantly higher than that of rifampin when both drugs were given in the same dosage. Moreover, when mice were fed a KRM-1648-containing diet (0.00004%-0.0004%), the drug displayed an even higher efficacy against M. leprae infection, causing an almost 4-log decrease in the number of leprosy bacilli in the infected foot pad compared to untreated controls.

Topics: Administration, Oral; Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Leprostatic Agents; Leprosy; Mice; Mice, Inbred BALB C; Mice, Nude; Mycobacterium leprae; Rifampin; Rifamycins

Ofloxacin (OFLX), having superior antileprosy activity among the various quinolones, was studied for its combined therapeutic efficacy with rifampin (RMP) against Mycobacterium leprae infection induced in nude mice. When OFLX (3 mg/mouse) was given to infected mice in combination with RMP (0.01 mg/mouse) by gavage once daily six times per week, from day 31 to day 80 postinfection, a significant combined effect was observed. This study demonstrates the possibility of using OFLX in multidrug regimens for the clinical control of bacilliferous leprosy patients.

Topics: Animals; Disease Models, Animal; Drug Therapy, Combination; Female; Leprosy; Mice; Mice, Inbred BALB C; Mice, Nude; Ofloxacin; Quinolones; Rifampin

Two combinations of antibiotics, clindamycin with rifampicin and cloxacillin with netilmicin, were investigated for their activity against two strains of Staphylococcus aureus (a sensitive reference strain and a methicillin-resistant clinical isolate) by means of the in vitro checkerboard technique and an in vivo infected mouse model. The mouse model allowed drug interactions to be evaluated both from the changes in the number of bacteria surviving treatment and from the measured exposure to antibiotics at the site of infection. Specimens from the latter were evaluated twice (day 0 and day 2) in each experiment. The combination of cloxacillin and netilmicin exhibited a synergistic effect against the reference strain both in vitro and in vivo, whereas synergism was obtained under in vitro conditions only against the methicillin-resistant strain. The clindamycin and rifampicin combination acted synergistically or indifferently against both strains in vitro and at day 0 of the in vivo experiments. In contrast, on day 2 of infection, this combination had significantly greater bactericidal effect (synergism) compared to the combination of cloxacillin and netilmicin. These results illustrate the difficulties of interpreting in vitro results for clinical use.

Topics: Animals; Clindamycin; Cloxacillin; Disease Models, Animal; Drug Interactions; Drug Therapy, Combination; Female; Humans; Mice; Mice, Inbred BALB C; Microbial Sensitivity Tests; Netilmicin; Rifampin; Staphylococcal Infections; Staphylococcus aureus

The activity of clarithromycin alone and in combination with other antimycobacterial agents was evaluated in the beige (C57BL/6J bgj/bgj) mouse model of disseminated Mycobacterium avium complex (MAC) infection. A dose-response experiment was performed with clarithromycin at 50, 100, 200, or 300 mg/kg of body weight administered daily by gavage to mice infected with approximately 10(7) viable MAC. A dose-related reduction in spleen and liver cell counts was noted with treatment at 50, 100, and 200 mg/kg. The difference in cell counts between treatment at 200 and 300 mg/kg was not significant. Clarithromycin at 200 mg/kg of body weight was found to have activity against three additional MAC isolates (MICs for the isolates ranged from 1 to 4 micrograms/ml by broth dilution). Clarithromycin at 200 mg/kg in combination with amikacin, ethambutol, temafloxacin, or rifampin did not result in increased activity beyond that seen with clarithromycin alone. Clarithromycin in combination with clofazimine or rifabutin resulted in an increase in activity beyond that seen with clarithromycin alone. The combination of clarithromycin with clofazimine or rifabutin should be considered for evaluation in the treatment of human MAC infections.

Topics: Amikacin; Animals; Anti-Infective Agents; Antitubercular Agents; Clarithromycin; Clofazimine; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Therapy, Combination; Ethambutol; Female; Fluoroquinolones; Humans; Mice; Mice, Inbred C57BL; Mycobacterium avium; Mycobacterium avium Complex; Quinolones; Rifabutin; Rifampin; Rifamycins; Time Factors; Tuberculosis

The bactericidal activities against Mycobacterium leprae of single or multiple doses of various combinations of new antileprosy drugs [minocycline (MINO), clarithromycin (CLARI), ofloxacin (OFLO), and sparfloxacin (SPFX)] and/or rifampin (RMP) were titrated in immunocompetent mice by the proportional bactericidal method. Drugs were administered by gavage at the following dosages (mg/kg) per dose: RMP 10, MINO 25, CLARI 100, OFLO 150, and SPFX 50. All 15 regimens exerted significant bactericidal activities, at least 96% of viables were killed. The activity of a single dose MINO + CLARI was only slightly inferior to that of RMP, and the activities of a single dose OFLO/SPFX + MINO + CLARI were similar to that of RMP. This suggests that either MINO + CLARI or OFLO/SPFX + MINO + CLARI may be administered once monthly together with RMP 600 mg for the treatment of multibacillary (MB) leprosy, and monthly administration of MINO + CLARI or OFLO/SPFX + MINO + CLARI may also be employed for the treatment of RMP-resistant MB leprosy. Because the killing effects of multiple doses of the combinations were so powerful, comparison of the bactericidal activities of these regimens was beyond the sensitivity of the immunocompetent mouse model, and are being tested in the nude mouse model. Although SPFX is more active against M. leprae than OFLO on a weight-to-weight basis, when both drugs were administered in mice at dosages equivalent to clinically tolerated dosages in humans, SPFX did not show more superiority than OFLO, and its real advantage over OFLO in the treatment of leprosy remains unclear.

Topics: Animals; Clarithromycin; Disease Models, Animal; Female; Fluoroquinolones; Foot; Hindlimb; Immunocompetence; Leprostatic Agents; Leprosy; Mice; Microbial Sensitivity Tests; Minocycline; Mycobacterium leprae; Ofloxacin; Quinolones; Rifampin

The bactericidal effect of a new quinolone, ofloxacin (OFLO), was determined on an established Mycobacterium leprae infection in nude mice. Various drug regimens, including combinations of drugs, were examined for different treatment periods. OFLO and rifampin (RMP) individually failed to produce significant killing after treatment with a single large dose. However, when single large doses of OFLO and RMP were given in combination, a 100-fold reduction in viability was achieved. For a longer period of treatment both of these drugs, at lower doses, produced a moderate reduction in viability. The addition of dapsone to the lower dose of OFLO resulted in a significant reduction in viability, while lower doses of RMP and OFLO together produced a moderate reduction in viability.

Topics: Animals; Dapsone; Disease Models, Animal; Drug Therapy, Combination; Leprosy; Mice; Mice, Nude; Mycobacterium leprae; Ofloxacin; Rifampin; Serum Bactericidal Test

A plasmapheresis (PA) model was developed to be used in chronic rabbit experiments. Test results obtained in 96 generalized tuberculosis animals demonstrated a more benign tuberculosis process in animals subjected to plasmapheresis, which was confirmed by parameters of the coefficients of mass and indices of animals' organ affecting, findings of the cation-lysosomal test and peptide molecules content in the peripheral blood. Rabbit studies involving registration of bromsulphalein half-life, hepatic blood flow and relative parenchymatous clearing showed that the isoniazide and rifampicin action significantly decreased under the PA influence. Studies in a hospital accommodating 90 patients with different renal tuberculosis forms and poor tuberculostatic tolerance showed that PA promoted restoration of tolerance to specific preparations and renal function improvement. PA was found to be practicable and safe method which relieves side effects of antituberculous preparations and contributes to tuberculosis treatment efficiency.

Topics: Animals; Chemical and Drug Induced Liver Injury; Combined Modality Therapy; Disease Models, Animal; Drug Tolerance; Humans; Isoniazid; Mycobacterium bovis; Plasmapheresis; Rabbits; Rifampin; Tuberculosis, Pulmonary; Tuberculosis, Renal

The activity of rifapentine (MDL 473) was evaluated in the beige (C57BL/6J-bgj/bgj) mouse model of disseminated Mycobacterium avium infection. Approximately 10(7) cfu of M. avium, serotype 1, were given iv. Seven days later treatment was started with intraperitoneal rifapentine at 20 mg/kg of body weight. Treatment was given daily for five days followed by twice weekly for three weeks. The mice were killed two days after the last dose. Spleens, livers and lungs were homogenized and cfu/organ determined. Analysis of variance and Tukey honestly significant difference tests indicated that rifapentine reduced cfu in each of the organs compared with untreated controls. A dose-response experiment was performed with a daily rifapentine dose of 10, 20 or 40 mg/kg administered intraperitoneally. Dose-related reductions in cfu counts were observed in each of the organs. The activity of oral rifapentine at 20 mg/kg was demonstrated in a comparative experiment with rifampicin at 20, 40 or 60 mg/kg. Rifapentine significantly reduced cfu counts in organs compared with rifampicin. Rifapentine should be considered for further evaluation in the treatment of M. avium complex infection in humans.

Topics: Administration, Oral; Animals; Antitubercular Agents; Biological Availability; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Injections, Intraperitoneal; Male; Mice; Mice, Inbred C57BL; Mycobacterium avium; Rifampin; Tuberculosis

The experiments showed that in a dose of 35-70 mg/kg rifampicin inhibited reproduction of the fixed rabies virus in the brain of infected animals. The drug had no inhibitory effect on synthesis of the virus-neutralizing antibodies after vaccination. Combination of rifampicin with antirabies gamma-globulin had a marked synergistic effect. The animal survival after the combination use amounted to 75-100 per cent and depended on the infective dose of the virus and the scheme of the drug administration. It was concluded that rifampicin might be used in complex therapy of rabies during the incubation period (along with gamma-globulin and the vaccine) for inhibiting virus reproduction at early infection stages.

Topics: Adjuvants, Immunologic; Animals; Antibodies, Viral; Antiviral Agents; Disease Models, Animal; Drug Therapy, Combination; gamma-Globulins; Immunization, Passive; Mice; Rabies; Rabies virus; Rifampin; Virus Replication

Isoniazid, rifampicin and ethambutol administered in equimolecular dosages (50, 250 and 100 mg/kg, respectively) for 4 days caused liver affection. This was manifested by elevated activity of serum aminotransferases and alkaline phosphatase, inhibition of lipid peroxidation of hepatocyte membranes and antioxidative system dysfunctions. Isoniazid and rifampicin were proved to be most hepatotoxic. The combined use of antituberculous drugs increases their membrane-damaging action, especially when isoniazid and rifampicin are used together, but mostly when isoniazid in combination with rifampicin and ethambutol is applied.

Topics: Animals; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Dose-Response Relationship, Drug; Ethambutol; Isoniazid; Liver; Liver Function Tests; Male; Rats; Rifampin

Two-week administration of isoniazid, rifampicin (50 mg/kg and pyrazinamide (1,5 g/kg) to white rats brings about liver affection characterized by a higher activity of alanine and aspartate aminotransferases, lipid peroxidation activation and bile production inhibition. With the liver affected by antituberculous drugs, protective action is provided by acetate tocopherol an antioxidant, and piracetam riboxin and pyriditol, antihypoxic agents.

Topics: Animals; Antioxidants; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Hepatitis, Animal; Inosine Diphosphate; Isoniazid; Male; Piracetam; Pyrazinamide; Rats; Rifampin; Vitamin E

Because persistence of infections associated with prosthetic material despite the use of appropriate antibiotics is a major clinical problem, the antimicrobial susceptibility of bacteria responsible for a chronic subcutaneous tissue cage infection in rat was investigated ex vivo. Three to 6 weeks after the initiation of infection, suspensions of two strains of Staphylococcus aureus recovered from the foreign body surface and surrounding fluid were exposed to either oxacillin, vancomycin, fleroxacin, gentamicin, or rifampin. The MBCs of these bacteria were markedly elevated, in most cases 128 to greater than 256 times higher than the MBC of batch culture S. aureus in either logarithmic or stationary phase. Kinetic studies showed the bacteria did not grow when incubated for 2 h in Mueller-Hinton broth, possibly reflecting dormancy. Their killing was slow and incomplete by all antibiotics at greater than 8 times their MIC. These data provide direct evidence of a decreased susceptibility of S. aureus to the killing effect of antimicrobials during chronic foreign body infections in vivo.

Topics: Animals; Anti-Bacterial Agents; Anti-Infective Agents; Ciprofloxacin; Diffusion Chambers, Culture; Disease Models, Animal; Drug Resistance, Microbial; Fleroxacin; Foreign Bodies; Gentamicins; Kinetics; Microbial Sensitivity Tests; Oxacillin; Penicillin Resistance; Rats; Rats, Inbred Strains; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Vancomycin

Comparative efficacy of the use of injection and oral dosage forms of rifampicin in the subtherapeutic doses in combination with peptidoglycan , an immunomodulator of microbial origin, was studied in respect to experimental anthracic infection with application of multifactorial analysis. It was shown that the antibiotic and immunomodulator had a pronounced synergistic effect. Polynomial statistic models were developed and nomograms or equal level curves defining the survival rate and average life-span (ALS) of the experimental animals within a wide range of the antibiotic and immunomodulator doses and the peptidoglycan dosing time were plotted. The combined use of the injection rifampicin in the subtherapeutic doses and the immunomodulator provided a significant increase in the survival rate and ALS, whereas the use of the oral antibiotic in combination with the immunomodulator increased only the ALS and not the survival rate. Multifactorial analysis proved to be an optimal methodical approach to comparative study of various antibiotic dosage forms used in combination with immunomodulators under experimental conditions.

Topics: Adjuvants, Immunologic; Administration, Oral; Animals; Anthrax; Disease Models, Animal; Drug Therapy, Combination; Factor Analysis, Statistical; Injections, Intraperitoneal; Male; Mice; Peptidoglycan; Rifampin

BALB/c mice inoculated nasally with Acanthamoeba culbertsoni, resulting in amebic encephalitis and death 3-7 days, were treated with rifampicin prophylactically (daily for 2 days with 75 and 100 mg/kg) and after infection (daily for 5 days with doses of 10-100 mg/kg). Prophylactic treatment resulted in full protection against infection, as assessed by absence of symptoms of central nervous system malfunction and negative brain culture 10 days after inoculation. Curative treatment was effective at the same doses; however, at doses of 10, 25, and 50 mg/kg, only two of six animals were free of symptoms and infection.

Topics: Acanthamoeba; Amebiasis; Animals; Disease Models, Animal; Female; Male; Meningitis; Mice; Mice, Inbred BALB C; Rifampin

Isolates of Legionella pneumophila serogroup 1, obtained from guinea pigs with experimentally induced Legionnaires disease, were tested for rifampin resistance. Thirteen isolates were from animals treated with rifampin alone, four isolates were from animals treated with saline, and three isolates each were from animals treated with erythromycin or erythromycin plus rifampin; all of these isolates were derived from the same parent strain, F889. Most of the isolates were obtained from rifampin-treated animals that survived infection but had persistence of bacteria in their lungs at necropsy. No differences in rifampin agar dilution MICs were detected for the 23 isolates and parent strain that were tested. None of the 13 isolates from animals treated with rifampin alone had a high number of resistant organisms detected by using a rifampin gradient plate assay. Thirteen isolates plus the parent strain were tested by using a quantitative method of determining resistance frequency. Considerable heterogeneity among isolates was observed, but there was no evidence of increased resistance for any treatment group. The range of rifampin resistance frequencies was 10(-7) to 10(-8). No evidence for rifampin-induced resistance of L. pneumophila was found in this study.

Topics: Animals; Disease Models, Animal; Drug Resistance, Microbial; Guinea Pigs; Legionella; Legionnaires' Disease; Microbial Sensitivity Tests; Rifampin

Multifactorial analysis of the combined use of rifampicin and an immunomodulator of the microbial origin, such as peptidoglycan, was performed on a model of experimental Q fever in albino mice. On the basis of the experimental results, statistic polynomial models describing the weight of the murine spleens and the titers of the complement-binding antibodies were designed. It was shown that the action of the immunomodulator and antibiotic was highly synergistic with respect to the chemotherapeutic activity and antibody titers. The preventive use of the immunomodulator yielded a 30-fold decrease in a rifampicin therapeutic dose. The use of the immunomodulator also provided a pronounced immunomodulating effect with respect to humoral immunity. Nomographs for optimizing the dose-time parameters of the antibacterial and immunomodulating therapy were plotted.

Topics: Adjuvants, Immunologic; Animals; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Immune Tolerance; Mice; Peptidoglycan; Q Fever; Rifampin

We used the guinea pig as an experimental model to investigate the pathogenicity of Mycobacterium tuberculosis. Sputum samples were injected subcutaneously into guinea pigs and the animals were killed and an autopsy performed after eight weeks. The likelihood of the sputum samples producing tuberculosis in the guinea pig was related to culture positivity rather than to duration of chemotherapy. This study does not support the belief that a change in pathogenicity occurs during treatment of pulmonary tuberculosis.

Topics: Animals; Anti-Bacterial Agents; Antitubercular Agents; Disease Models, Animal; Drug Therapy, Combination; Ethambutol; Fluorescent Antibody Technique; Guinea Pigs; Humans; Injections, Subcutaneous; Isoniazid; Mycobacterium tuberculosis; Rifampin; Sputum; Tuberculosis, Pulmonary

A novel model of experimental foreign body infection was developed in rats: four perforated Teflon tissue cages per animal were implanted subcutaneously and 3 to 4 weeks later were infected with 0.5 x 10(5) to 2 x 10(5) CFU of methicillin-resistant Staphylococcus aureus. After 2 weeks, the number of CFU in the cage fluid was determined [day 1 mean, (7.25 +/- 0.79) log10 CFU/ml], and treatment with vancomycin (50 mg/kg twice a day [BID]), fleroxacin (50 mg/kg BID), or fifampin (25 mg/kg BID), alone and in combination, was initiated for a duration of 6 days. Concentrations of antibiotics in cage fluids were in the range of those encountered in clinical conditions. Eighteen hours after the last injection (day 7), the number of CFU in the cage fluid was determined and the difference between day 1 and day 7 values was calculated. Rifampin, alone and in combination with fleroxacin or vancomycin, was the most effective regimen in reducing the bacterial counts in the tissue cage fluids [(1.87 +/- 1.44, 2.18 +/- 1.02, and 2.55 +/- 1.09 log10) CFU/ml, P less than 0.001, respectively]. After treatment, cage fluids and cages were analyzed for resistant bacteria. Resistance to rifampin occurred in 15 of 19 cages in animals treated with rifampin alone and in 4 of 25 in animals treated with rifampin plus vancomycin. We detected no development of resistance to rifampin in animals treated with rifampin plus fleroxacin or to fleroxacin in animals treated with this antimicrobial agent. In conclusion, regimens including rifampin alone or in combination with vancomycin or fleroxacin were an effective treatment of foreign body infection due to methicillin-resistant S. aureus in reducing bacteria counts, but rifampin monotherapy was compromised by significant emergence of resistance. The combined therapy of fleroxacin with rifampin prevent development of resistance to rifampin.

Topics: Animals; Anti-Bacterial Agents; Ciprofloxacin; Disease Models, Animal; Drug Therapy, Combination; Fleroxacin; Foreign-Body Reaction; Male; Methicillin Resistance; Microbial Sensitivity Tests; Rats; Rats, Inbred Strains; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Vancomycin

The efficacies of the quinolones ciprofloxacin and pefloxacin alone and in combination with rifampin were compared with those of vancomycin alone and in combination with rifampin in a rat model of chronic osteomyelitis caused by methicillin-resistant Staphylococcus aureus. Neither the quinolones nor vancomycin alone was effective in reducing titers of organisms in bone after therapy, while rifampin alone was effective. All combination regimens with rifampin were more effective than the regimen with rifampin alone was, although these differences did not achieve statistical significance. Rifampin-resistant isolates were detected rarely. Quinolone-rifampin combination regimens may offer a nonparenteral option for the treatment of chronic osteomyelitis caused by methicillin-resistant S. aureus.

Topics: Animals; Chronic Disease; Ciprofloxacin; Disease Models, Animal; Drug Therapy, Combination; Male; Methicillin; Osteomyelitis; Pefloxacin; Penicillin Resistance; Rats; Rats, Inbred Strains; Rifampin; Staphylococcal Infections; Vancomycin

Topics: Animals; Ciprofloxacin; Disease Models, Animal; Drug Therapy, Combination; Isoniazid; Male; Mice; Rifampin; Tuberculosis

Five antimicrobial drugs (ciprofloxacin, clindamycin, imipenem, penicillin G, and rifampin) were examined for therapeutic efficacy in a murine model gas gangrene due to Clostridium perfringens type A, following infection with large bacterial inocula. Imipenem was effective against all 6 strains of C. perfringens; conversely, penicillin G failed against these 6 strains. Ciprofloxacin, clindamycin, and rifampin occupied intermediate positions.

Topics: Animals; Ciprofloxacin; Clindamycin; Clostridium perfringens; Disease Models, Animal; Gas Gangrene; Imipenem; Mice; Microbial Sensitivity Tests; Penicillin G; Rifampin

Topics: Aerosols; Air Microbiology; Animals; Disease Models, Animal; Guinea Pigs; Legionnaires' Disease; Rifampin

Efficacy of a new rifampicin dosage form developed at the All-Union Research Institute of Antibiotics was studied on dogs with extensive destructive tuberculosis of the lungs. Intracavernous instillation and rapid intravenous administration (RIA) of the drug in combination with 10 per cent solution of isoniazid and intramuscular administration of streptomycin were used. Intracavernous instillation of rifampicin in combination with 10 per cent solution of isoniazid was performed under the control of an x-ray unit with an image converter tube or with the developed administration procedure through an indwelling catheter. Intracavernous administration of the drugs was alternated with their RIA: either one-stage administration of the antibiotic in daily half doses to each cavern followed by RIA every second day or RIA of a daily half dose in the morning followed by intracavernous instillation of the second half dose to one cavern in 5-6 hours and the second half dose to the other cavern on the next day. Intracavernous instillation of rifampicin in combination with isoniazid together with their RIA in treatment of extensive destructive tuberculosis of the lungs provided 100 per cent elimination of tubercle bacilli in the internal organs of all the dogs and closing of the caverns with cicatrization in 70 per cent of the dogs and formation of microcavities in 30 per cent of the dogs within 30 days.

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Dogs; Drug Evaluation, Preclinical; Drug Therapy, Combination; Female; Injections, Intramuscular; Injections, Intravenous; Instillation, Drug; Male; Rifampin; Solubility; Time Factors; Tuberculosis, Pulmonary

The efficacy of treating established vascular graft infections with rifampin and clindamycin (preferentially concentrated in leukocytes) and cefazolin (not concentrated in leukocytes) was studied in a canine model. Infrarenal aortic, 6 mm by 6 cm knitted Dacron double velour grafts were implanted and infected with 10(8) colony-forming units (CFU) of coagulase-positive Staphyloccus aureus organisms injected intravenously immediately after graft placement. Antibiotic therapy was instituted at 3 months postimplantation. Three groups were studied: (I) untreated controls (n = 3); (II) therapy with intravenous cefazolin 15 mg/kg/8 hr for 28 days (n = 7); and (III) combined therapy with intravenous rifampin 13 mg/kg/24 hr and intravenous clindamycin 13 mg/kg/8 hr for 28 days (n = 7). Grafts were removed for quantitative bacteriologic studies after the 28-day course of therapy. Two group I control grafts remained patent with 6.4 X 10(6) and 8.1 X 10(3) CFU S. aureus/gm of graft. The third control graft was thrombosed. Two group II animals demonstrated 1.6 X 10(7) and 2.3 X 10(5) CFU S. aureus organisms/gram of graft, respectively; the remaining five group II grafts were free of organisms. All group III grafts were sterile--a significant difference (p less than 0.05) from group I grafts. In this experimental model, established prosthetic graft infections were eradicated by intensive treatment with antibiotics preferentially concentrated in leukocytes.

Topics: Animals; Blood Vessel Prosthesis; Cefazolin; Clindamycin; Disease Models, Animal; Dogs; Drug Therapy, Combination; Female; Leukocytes; Rifampin; Staphylococcal Infections; Surgical Wound Infection

Implanted foreign bodies are highly susceptible to pyogenic infection. Whereas infection up to 3 months after surgery is probably due to perioperative bacterial contamination, little is known about the pathogenesis of late prosthetic infections. We employed an animal model to determine whether subcutaneously implanted foreign bodies were susceptible to experimental bacteremia. Tissue cages were implanted into guinea pigs, which were infected at the earliest 4 weeks later by intracardiac injection of Staphylococcus aureus Wood 46. The injection of 2 X 10(6) cfu did not result in any infection. Inoculation of 5 X 10(7) cfu resulted in a bacteremia of 10(2)-10(3) cfu/ml after 5 min and led to 11/26 selective tissue cage infections with no microbiological evidence of infection elsewhere. Higher inocula caused systemic infections with foci in different organs. Rifampin (7.5 mg/kg b.i.d.) was administered for 48 h, starting at different times after infection to establish the best timing for efficacious short-term therapy. When treatment was begun 1 h before or 3 h after inoculation, complete protection was observed, whereas 1/12 and 3/15 tissue cages remained infected when the first dose was not given until 24 h and 48 h, respectively, after inoculation. These experiments illustrate that implanted prostheses are highly susceptible even to bacteremias with low density of microorganisms. Prophylaxis can prevent such infections, whereas delayed short-term treatment may fail.

Topics: Animals; Disease Models, Animal; Foreign-Body Reaction; Guinea Pigs; Rifampin; Sepsis; Time Factors

Although multiple antibiotic strategies to eradicate group B streptococci (GBS) from colonized infants and women have been utilized, no regimen has been successful in eliminating GBS carriage reliably. Because rifampin has been successful in terminating nasopharyngeal colonization with other bacteria, we tested both the in vitro sensitivity of GBS to rifampin and the in vivo efficacy of rifampin in eliminating GBS from a new animal model of nasally colonized infant rats. The minimal inhibitory concentration of rifampin for 18 clinically derived strains of type III GBS ranged from 0.1 to 0.4 micrograms/ml. Atraumatic nasal inoculation of infant rats with 10(6)-10(7) colony forming units of GBS twice daily for 4 days resulted in heavy asymptomatic carriage for at least 10 days. Colonized animals were divided into four treatment groups: saline, oral rifampin, intraperitoneal penicillin, or oral rifampin plus intraperitoneal penicillin. Treatment was administered every 12 h for 4 days. All 78 saline-treated controls and 47 of 52 (90.4%) penicillin-treated animals had continued GBS carriage 36 h after completion of therapy. In contrast, only 18 of 52 (34.6%) rifampin-treated animals and seven of 54 (13.0%) rifampin plus penicillin-treated animals remained GBS-positive. No rifampin-resistant GBS were detected. Combination rifampin plus penicillin therapy was significantly more effective in terminating GBS carriage compared to saline or penicillin alone (p less than 0.0001) or to rifampin (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Animals, Newborn; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Therapy, Combination; Nasal Mucosa; Penicillins; Rats; Rats, Inbred Strains; Rifampin; Streptococcal Infections; Streptococcus agalactiae

Studies of in vitro and in vivo bactericidal interactions of vancomycin plus rifampin against Staphylococcus aureus have yielded conflicting results. In this study the efficacy of this drug combination in experimental endocarditis due to a methicillin-resistant strain of S. aureus was investigated. Left-sided endocarditis was induced in 84 rabbits by an infecting strain that had been found to be synergistically killed by vancomycin plus rifampin in vitro when tested by the timed-kill curve technique; in contrast, the checkerboard technique had indicated that the two drugs were antagonistic against this strain. Infected animals received no therapy, vancomycin alone (30 mg/kg per day), rifampin alone (20 mg/kg per day), or both drugs (in the same doses). The combination was significantly more effective than the single-drug regimens in terms of (1) reduction of mean methicillin-resistant S. aureus vegetation titers (P less than .05-.0005), (2) rate and incidence of sterilization of vegetations (P less than .0005), and (3) rate of "radical" cure of endocarditis (P less than .005). Vancomycin alone and vancomycin plus rifampin were equally effective in reducing mortality and sterilizing renal abscesses. The use of vancomycin prevented the in vivo development of resistance to rifampin. No evidence that rifampin exerted an antagonistic effect on the in vivo bactericidal activity of vancomycin was found.

Topics: Animals; Creatinine; Disease Models, Animal; Drug Therapy, Combination; Endocarditis, Bacterial; Kidney; Methicillin; Microbial Sensitivity Tests; Penicillin Resistance; Rabbits; Rifampin; Staphylococcal Infections; Staphylococcus aureus; Vancomycin

Laboratory tests of antibiotic activity in vitro, ranging from simple MIC determinations to sophisticated, computerized models for studying the effects of simulated plasma concentration-time curves of antibiotics in broth, differ inherently from tests in vivo in both the general and specific variables. There are therefore likely to be discrepancies between the results obtained. Apart from the obvious lack of host-defence mechanisms in the in-vitro tests systems, the reasons for these discrepancies have still not been fully elucidated. For the time being, it seems unrealistic to expect that in-vitro tests could be developed that would make it possible to predict the efficacy of any antibiotic against any specific infection in vivo.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Bacterial Infections; Disease Models, Animal; Mice; Microbial Sensitivity Tests; Rifampin

10 different strains of Listeria monocytogenes tested in vitro were found to be susceptible to rifampicin showing minimal inhibitory concentrations between 0.0075 and 0.06 microgram/ml. Mice infected with a virulent strain of L. monocytogenes were treated with this antibiotic. Bacterial counts rapidly declined. In dextran sulfate-treated animals, deprived of their macrophage system and consequently highly susceptible to Listeria infection, rifampicin was able to protect the animals. Furthermore, nude athymic mice, chronically infected with L. monocytogenes, were also nearly cured. A few remaining bacteria, however, started to multiply after cessation of therapy, so that a relapse was noted. Development of resistance of L. monocytogenes to rifampicin during treatment was not observed.

Topics: Animals; Dextran Sulfate; Dextrans; Disease Models, Animal; Female; Immunity, Cellular; Listeria monocytogenes; Listeriosis; Macrophages; Mice; Mice, Nude; Microbial Sensitivity Tests; Rifampin

Rifampicin and rifapentine were used in the treatment of Listeria monocytogenes infections in normal mice and congenitally athymic (nude) mice. Results were compared with untreated controls and with the results obtained from a previous study of ampicillin in which this model was used. Low doses of rifampicin or rifapentine were adequate to cure normal mice. The efficacy of these antibiotic treatment schedules was lost in nude mice. Prolonged antibiotic treatment schedules with increased dosages were also unsuccessful. These studies show that rifampicin and rifapentine , two antimicrobial agents being capable of destroying intracellular bacteria, were not effective in curing the Listeria infection in mice with impaired host defenses.

Topics: Animals; Anti-Bacterial Agents; Disease Models, Animal; Female; Half-Life; Listeriosis; Mice; Mice, Nude; Rifampin; T-Lymphocytes

The effects of various chemotherapeutic regimens were investigated in ddY mice infected intravenously with a mouse-virulent strain, 31F093T, of Mycobacterium avium-intracellulare. Evaluation of therapeutic effects was based on serial counts of viable bacilli in the lung, the spleen, and the kidney, as well as on weight and extent of gross diseases of the organs, and on histopathologic examination. Kanamycin alone was effective against the infection. The combination of ethambutol and rifampin with kanamycin (KM-EMB-RMP) decreased counts in the lung. In another 3-drug regimen (kanamycin, ethionamide, and cycloserine), the effect was similar. Two 4-drug regimens, KM-EMB-RMP-CEX and KM-EMB-RMP-MINO, as well as a 5-drug regimen, KM-EMB-RMP-CS-INH, were also compared with the above 3-drug regimens, and only the 5-drug regimen decreased counts in the lung more than the 3-drug regimens did. Even the 5-drug regimen, however, could not eradicate the mycobacteria in the organs of mice, which demonstrates the inveteracy of M. avium-intracellulare infection. The control mice consistently showed grossly visible disease of the lung at 6 wk of infection, and the histopathologic findings were granuloma (3 to 6 wk of infection) and diffuse proliferative change beyond 9 weeks of infection, which was persistent and slowly progressive. The spleens and livers showed extensive granulomatous changes. The subacuteness of grossly visible lung disease with significant multiplication of bacilli in the organ of the control mice in the present murine model should prove useful in evaluating experimental chemotherapy of M. avium-intracellulare infection.

Topics: Animals; Antitubercular Agents; Chronic Disease; Cycloserine; Disease Models, Animal; Drug Therapy, Combination; Ethambutol; Kanamycin; Liver; Lung; Male; Mice; Mycobacterium avium; Mycobacterium Infections; Mycobacterium Infections, Nontuberculous; Rifampin; Spleen; Time Factors

Topics: Clofazimine; Dapsone; Disease Models, Animal; Drug Resistance, Microbial; Humans; Leprosy; Mycobacterium leprae; Rifampin; Syndrome; T-Lymphocytes

The activities of a range of antibiotics on Staphylococcus aureus organisms that survive within bovine neutrophils in vitro were studied in mice. Cloxacillin, floxacillin, and cephradine failed to kill intracellular staphylococci but increased the organisms' sensitivity to killing by lysostaphin after neutrophil disruption. Fusidate and clindamycin caused an apparent small reduction in viable intraleukocytic S aureus, whereas novobiocin did not demonstrate intracellular activity. Substantial intracellular bactericidal effects were shown in vitro by rifampin and rifamycin SV, even at concentrations in slight excess of the minimum inhibitory concentration. In a mouse model of chronic mastitis, intramammary therapy with rifampin was more effective in reducing viable S aureus in infected glands than was therapy with rifamycin SV.

Topics: Animals; Anti-Bacterial Agents; Cattle; Cloxacillin; Disease Models, Animal; Drug Therapy, Combination; Female; Leukocytes; Lysostaphin; Mastitis; Mastitis, Bovine; Mice; Neutrophils; Penicillin Resistance; Pregnancy; Rifampin; Rifamycins; Rodent Diseases; Staphylococcal Infections; Staphylococcus aureus

Antibiotic therapy of methicillin-resistant Staphylococcus epidermidis endocarditis was investigated with the rabbit endocarditis model. Time-kill studies in vitro demonstrated that gentamicin and rifampin had the most rapid early bactericidal rates. With rifampin alone, rifampin-resistant subpopulations emerged. Combinations of antibiotics with gentamicin or rifampin in vitro did not significantly alter the killing rate but prevented emergence of subpopulations resistant to the latter. In the rabbit endocarditis model, gentamicin and vancomycin were the most effective single antibiotic regimens in terms of ability to reduce the bacterial densities on cardiac valve vegetations. Five treatment regimens were equally effective, including vancomycin, gentamicin, vancomycin plus rifampin or gentamicin, and rifampin plus gentamicin. The three-drug combination of vancomycin, rifampin, and gentamicin did not significantly improve the results. Cephalothin therapy was significantly less effective than any of the regimens noted above. It was no more effective than no treatment at 2 days and was only slightly more effective at 4 days. This result with cephalothin treatment was not predicted by routine types of in vitro antibiotic susceptibility testing. Treatment of rabbits with methicillin or cephalothin was associated with an increase in the subpopulation of bacteria resistant to the respective drugs. A number of regimens show potential for therapy of these infections, including vancomycin plus rifampin or gentamicin, rifampin plus gentamicin, and vancomycin alone.

Topics: Animals; Anti-Bacterial Agents; Cephalothin; Disease Models, Animal; Drug Therapy, Combination; Endocarditis; Gentamicins; Methicillin; Microbial Sensitivity Tests; Penicillin Resistance; Rabbits; Rifampin; Staphylococcal Infections; Vancomycin

Topics: Animals; Disease Models, Animal; Furosemide; Humans; Porphyrias; Rats; Rifampin; Risk; Valproic Acid

The dynamics of nasopharyngeal colonization, bacteremia, and transmission of infection due to Haemophilus influenzae type b in infant rats were studied. Intranasal inoculation resulted in nasal colonization in 99% and bacteremia in 88% of infant rats. H. influenzae type b was transmitted to 93% of exposed, uninoculated littermates. Pretreatment with burro antibody to H. influenzae type b prevented bacteremia but not nasal colonization. Rifampin, in a dose of 20 mg/kg twice daily for two days, was 97% and 100% effective in eradicating two strains of H. influenzae type b from the nasopharynx. Efficacies of 10 mg/kg twice daily and 5 mg/kg twice daily for two days were 86% and 6%, respectively. No rifampin-resistant isolates were encountered in animals still colonized after rifampin therapy. This model for haemophilus colonization and intralitter transmission could be used to evaluate other chemoprophylactic agents and may provide additional insight into the epidemiology and immunology of haemophilus infections.

Topics: Animals; Animals, Newborn; Antibodies, Bacterial; Disease Models, Animal; Female; Haemophilus Infections; Haemophilus influenzae; Nasopharyngeal Diseases; Nasopharynx; Pregnancy; Rats; Rifampin; Sepsis

Erythromycin and rifampicin (rifampin) were able to prevent death of guineapigs given intraperitoneal injections of the agent causing legionnaires' disease. Penicillin, chloramphenicol, tetracycline, and gentamicin showed no significant effect. On the basis of clinical experience and experimental observations, erythromycin is recommended for patients suspected to have legionnaires' disease. Combined therapy with erythromycin and rifampicin may be justified in patients with confirmed legionnaires' disease who are not responding to erythromycin alone or as part of a controlled antibiotic trial among suspected cases during an outbreak of legionnaires' disease.

Topics: Administration, Oral; Animals; Chloramphenicol; Disease Models, Animal; Drug Evaluation; Drug Evaluation, Preclinical; Drug Therapy, Combination; Erythromycin; Female; Gentamicins; Guinea Pigs; Injections, Subcutaneous; Legionnaires' Disease; Penicillins; Respiratory Tract Infections; Rifampin; Tetracycline

The influence of tsutsugamushi fever infection on the metabolism of blood lymphocytes of mice differing in susceptibility to Rickettsia tsutsugamushi and of rifampicine and tetracycline treatment was studied. In susceptible mice, the activity of oxidation-reduction processes in lymphocytes increased at 7--10 days of the disease and became normal upon recovery of the animals. In mice with low susceptibility this increase of the activity began and terminated much earlier, at 3--5 days. Treatment of the infection with antibiotics resulted in a rapid arrest of the disease and normalization of the lymphocyte activity. The relationship between susceptibility of the animals to R. tsutsugamushi and the activity of oxidation-reduction enzymes is discussed on the example of succinate dehydrogenase.

Topics: Animals; Antibodies, Bacterial; Disease Models, Animal; Lymphocytes; Mice; Orientia tsutsugamushi; Rifampin; Scrub Typhus; Succinate Dehydrogenase; Tetracycline

Recent immunologic and microbiologic evidence suggests that urothelial tumors may be caused by "C" type oncogenic viruses. Such viruses may exert their oncogenic potential in responce to stimulation by known chemical carcinogens. By means of a unique enzyme, reverse transcriptase, these viruses are able to incorporate genetic information into that of the host, and can thereby be transmitted vertically from generation to generation. An evaluation of the specific antiviral agents dimethylbenzyldemethl-rifampicin and streptovaricin-comples, which inhibit the enzyme reverse transcriptase, revealed no depay in the induction of bladder tumors by the chemical carcinogen, 2-formylamino-4-(5-nitro-2-furyl) thiazole (FANFT) in C3H mice. This observation suggests that the reproduction and release of virus may not be essential in the malignant transformation of bladder epithelial cells, but does not preclude the possiblity that inherited viral genetic information may be involved in the oncogenesis of bladder tumors.

Topics: Animals; Disease Models, Animal; FANFT; Genetic Code; Mice; Mice, Inbred C3H; Neoplasms, Experimental; Oncogenic Viruses; Reverse Transcriptase Inhibitors; Rifampin; RNA-Directed DNA Polymerase; Streptovaricin; Urinary Bladder Neoplasms

Topics: Animals; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Enterobacteriaceae; Enterobacteriaceae Infections; Escherichia coli; Mice; Mutation; Proteus vulgaris; Rifampin; Salmonella typhimurium; Shigella dysenteriae; Trimethoprim

Topics: Animals; Disease Models, Animal; Male; Mice; Mycobacterium; Rifampin; Streptomycin; Tuberculosis

The author discusses the conditions which an experimental pyelonephritis must fulfill to provide therapeutic results which will allow the assessment of new therapeutic agents. He subjects the chosen model to the therapeutic effect of four antibiotics and three antimicrobial drugs. A numeric value is given to the bacteriuria recession slope observed during the experiment. A comparison of the results being obtained with the bacteriological and pharmacological data normally evaluated, the author demonstrates the value of the present study. The analysis of the results collected during the tests shows that comparison between antibiotics are of greater value when they are of the same family. Nevertheless, the experimental pattern, when applied to antibiotics as different as kanamycine and cephalosporins, give a very good correlation particularly when the overstepping coefficient, as proposed by Canetti, is calculated on the results expressed as free products.

Topics: Administration, Oral; Animals; Anti-Bacterial Agents; Cefazolin; Cephaloridine; Cephalothin; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Resistance, Microbial; Female; Injections, Intramuscular; Kanamycin; Klebsiella Infections; Klebsiella pneumoniae; Nalidixic Acid; Nitroquinolines; Pyelonephritis; Rats; Rifampin; Sulfamethoxypyridazine; Urine

Topics: Animals; Chemical and Drug Induced Liver Injury; Disease Models, Animal; Galactosamine; Isoniazid; Liver; Male; Rats; Rifampin

Amphotericin B, the principal drug used for treating systemic mycoses, possesses undesirable toxic properties. The ability of this antibiotic to potentiate antifungal activity of other compounds suggests that lower doses of amphotericin B could be used in combination with a second drug without loss of therapeutic efficacy. In vitro tests demonstrated that amphotericin B potentiated rifampin against the mycelial growth phase of Coccidioides immitis but not against the spherule-endospore phase. Therapy for murine coccidioidomycosis with a combined amphotericin B-rifampin regimen was not better than treatment with amphotericin B alone; in fact, combined drugs may have been even less effective. This would have clinical significance for therapy of concurrent infections.

Topics: Amphotericin B; Animals; Coccidioides; Coccidioidomycosis; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Male; Mice; Rifampin

Following intravenous injection of mycobacteria in the mouse the bacilli are regularly found in the peripheral nervous system after the 5th day. The peripheral nerves and autonomic ganglia are involved at the level of the perineural cells and the sheath of Schwann. When the organisms are of low virulence (BCG, Mycobacterium intracellulare) the development of the nodules is limited. In the case of a virulent strain (Ravenel) extensive granulomas are found but epitheloid cells, always found in other organs, are constantly absent. In animals previously immunized, the bacilli seem to implant themselves as in the controls, but multiply more slowly; the nodules are more infrequent and the lymphoid infiltration appears earlier with the multiplication of interstitial cells.

Topics: Animals; BCG Vaccine; Disease Models, Animal; Ganglia, Autonomic; Injections, Intravenous; Mice; Mycobacterium; Mycobacterium bovis; Peripheral Nerves; Rifampin; Schwann Cells; Tuberculosis; Virulence

The total minimal inhibitory dose of rifampicin determined in the experimental mouse model, was found to be 10 mg/kg body weight, administered once a week for 6 weeks or once every 2 weeks for 12 weeks. From these and other results it is suggested that administration of RMP in human treatment can be reduced to a total amount of 7.2 either as a 600 mg dose once a week for 12 weeks or as a 900 mg dose once a week for 8 weeks. At present these regimens can only be used as an introductory treatment for multibacillary cases and are still too expensive for developing countries, but their efficacy should be evaluated in the field as sole treatments in tuberculoid cases, since they could signify a substantial economy for the management of the majority of leprosy infections.

Topics: Animals; Body Weight; Disease Models, Animal; Humans; Leprosy; Mice; Mice, Inbred Strains; Mycobacterium leprae; Rifampin; Time Factors

The rate at which various antimicrobial agents eradicated Staphylococcus aureus from cardiac vegetations in a rabbit model of endocarditis was studied. The rate at which various drugs and combinations killed high titers of bacteria in broth correlated with the relative effectiveness of the agents in vivo. Gentamicin plus penicillin proved to be synergistic in vitro and more effective in eradicating bacteria from cardiac vegetations in vivo than was penicillin alone. Vancomycin killed bacteria at a rate similar to that for the combination of penicillin and gentamicin, and the rate for cefazolin was similar to that for penicillin alone. Clindamycin was less effective in vivo and in vitro than penicillin. Therapy with rifampin led to the emergence of resistant organisms, and, when penicillin, this drug was less effective in vitro and in vivo than was penicillin alone. This model appears to offer an effective method for evaluation of antimicrobial treatment of staphylococcal endocarditis.

Topics: Animals; Anti-Bacterial Agents; Cephalothin; Clindamycin; Disease Models, Animal; Drug Therapy, Combination; Endocarditis, Bacterial; Gentamicins; Penicillins; Rabbits; Rifampin; Staphylococcal Infections; Time Factors; Vancomycin

Levels of rifampin, gentamicin, sisomicin, and cephalothin in normal and osteomyelitic rabbit bones were measured, and the efficacy of these drugs in the treatment of osteomyelitis was evaluated. Single drug regimens, including rifampin for 14 days and gentamicin, sisomicin, and cephalothin each for 28 days, were relatively ineffective (5%-33% sterile bone cultures). Rifampin, administered for 28 days, sterilized the bones of 55% of treated animals. The combination of gentamicin and rifampin, given for either 14 or 28 days, sterilized the bones of 67% of treated animals. The combinations of rifampin plus sisomicin and of rifampin plus cephalothin, given for 28 days, were significantly more effective than these agents alone, sterilizing 90%-95% of bones. The combination of rifampin, sisomicin, and cephalothin, given for only 14 days, sterilized the bones of all treated rabbits. Staphylococci isolated from the bones of therapeutic failures that had received rifampin alone or in combination with other antibiotics were highly resistant to rifampin (minimal inhibitory concentration, greater than 250 mug/ml), whereas the organisms recovered from animals not receiving rifampin remained sensitive. Results of in vitro studies of synergy and/or bactericidal activity of antibiotic combinations correlated with in vivo results in some, but not all, instances.

Topics: Animals; Anti-Bacterial Agents; Cephalothin; Disease Models, Animal; Drug Evaluation, Preclinical; Drug Resistance, Microbial; Drug Synergism; Drug Therapy, Combination; Gentamicins; Osteomyelitis; Rabbits; Rifampin; Sisomicin; Staphylococcus aureus

Topics: Administration, Oral; Agglutination Tests; Animals; Antibodies, Bacterial; Blood Bactericidal Activity; Coombs Test; Disease Models, Animal; Fluorescent Antibody Technique; Guinea Pigs; Isoniazid; Rifampin; Spleen; Time Factors; Tuberculin Test; Tuberculosis

Topics: Animals; Disease Models, Animal; Ethambutol; Mice; Rifampin; Tuberculosis

Topics: Animals; Bile; Carbon Tetrachloride Poisoning; Disease Models, Animal; Female; Liver Diseases; Male; Rats; Rifampin

Topics: Adipose Tissue; Adipose Tissue, Brown; Animals; Autopsy; BCG Vaccine; Disease Models, Animal; Histological Techniques; Macrophages; Mice; Mycobacterium bovis; Rifampin; Time Factors; Tuberculosis

Topics: Animals; Cornea; Disease Models, Animal; Dysentery, Bacillary; Epithelial Cells; Escherichia coli; Evaluation Studies as Topic; Guinea Pigs; Injections, Intramuscular; Kanamycin; Keratoconjunctivitis; Ophthalmic Solutions; Rifampin; Shigella; Shigella flexneri; Streptomycin; Tetracycline

Topics: Aniline Compounds; Animals; Dapsone; Disease Models, Animal; Drug Combinations; Ethionamide; Humans; Isoniazid; Leprosy; Mice; Models, Biological; Mycobacterium Infections; Phenazines; Pyrazines; Rabbits; Rifampin; Sulfonamides; Trimethoprim

Topics: Animals; Antitubercular Agents; Disease Models, Animal; Drug Resistance, Microbial; Drug Synergism; Isoniazid; Mice; Mycobacterium tuberculosis; Rifampin; Streptomycin; Tuberculosis, Pulmonary

Topics: Animals; Cell Count; Chronic Disease; Disease Models, Animal; Drug Synergism; Ethambutol; Ethionamide; Isoniazid; Lung; Mice; Placebos; Rifampin; Streptomycin; Tuberculosis

Topics: Animals; Communicable Diseases; Dapsone; Disease Models, Animal; Drug Resistance, Microbial; Hindlimb; Humans; Leprosy; Mice; Microscopy, Electron; Muscles; Mycobacterium leprae; Rifampin; Sciatic Nerve

Topics: Acute Disease; Animals; Bacteriuria; Behavior, Animal; Body Weight; Cephaloridine; Depression, Chemical; Disease Models, Animal; Escherichia coli; Escherichia coli Infections; Female; Kidney; Organ Size; Pyelonephritis; Rats; Rifampin